feat(gateway): add web search emulation for Anthropic API Key accounts

Inject web search capability for Claude Console (API Key) accounts that
don't natively support Anthropic's web_search tool. When a pure
web_search request is detected, the gateway calls Brave Search or Tavily
API directly and constructs an Anthropic-protocol-compliant SSE/JSON
response without forwarding to upstream.

Backend:
- New `pkg/websearch/` SDK: Brave and Tavily provider implementations
  with io.LimitReader, proxy support, and Redis-based quota tracking
  (Lua atomic INCR + TTL, DECR rollback on failure)
- Global config via `settings.web_search_emulation_config` (JSON) with
  in-process cache + singleflight, input validation, API key merge on
  save, and sanitized API responses
- Channel-level toggle via `channels.features_config` JSONB column
  (DB migration 101)
- Account-level toggle via `accounts.extra.web_search_emulation`
- Request interception in `Forward()` with SSE streaming response
  construction using json.Marshal (no manual string concatenation)
- Manager hot-reload: `RebuildWebSearchManager()` called on config save
  and startup via `SetWebSearchRedisClient()`
- 70 unit tests covering providers, manager, config validation,
  sanitization, tool detection, query extraction, and response building

Frontend:
- Settings → Gateway tab: Web Search Emulation config card with global
  toggle, provider list (add/remove, API key, priority, quota, proxy)
- Channels → Anthropic tab: web search emulation toggle with global
  state linkage (disabled when global off)
- Account Create/Edit modals: web search emulation toggle for API Key
  type with Toggle component
- Full i18n coverage (zh + en)

frontend/src/components/account/CreateAccountModal.vue

@@ -2325,6 +2325,22 @@
         </div>
       </div>
 
+      <!-- Anthropic API Key: Web Search Emulation -->
+      <div
+        v-if="form.platform === 'anthropic' && accountCategory === 'apikey'"
+        class="border-t border-gray-200 pt-4 dark:border-dark-600"
+      >
+        <div class="flex items-center justify-between">
+          <div>
+            <label class="input-label mb-0">{{ t('admin.accounts.anthropic.webSearchEmulation') }}</label>
+            <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+              {{ t('admin.accounts.anthropic.webSearchEmulationDesc') }}
+            </p>
+          </div>
+          <Toggle v-model="webSearchEmulationEnabled" />
+        </div>
+      </div>
+
       <!-- OpenAI OAuth Codex 官方客户端限制开关 -->
       <div
         v-if="form.platform === 'openai' && accountCategory === 'oauth-based'"
@@ -2830,6 +2846,7 @@ import ConfirmDialog from '@/components/common/ConfirmDialog.vue'
 import Select from '@/components/common/Select.vue'
 import Icon from '@/components/icons/Icon.vue'
 import ProxySelector from '@/components/common/ProxySelector.vue'
+import Toggle from '@/components/common/Toggle.vue'
 import GroupSelector from '@/components/common/GroupSelector.vue'
 import ModelWhitelistSelector from '@/components/account/ModelWhitelistSelector.vue'
 import QuotaLimitCard from '@/components/account/QuotaLimitCard.vue'
@@ -2980,6 +2997,7 @@ const openaiOAuthResponsesWebSocketV2Mode = ref<OpenAIWSMode>(OPENAI_WS_MODE_OFF
 const openaiAPIKeyResponsesWebSocketV2Mode = ref<OpenAIWSMode>(OPENAI_WS_MODE_OFF)
 const codexCLIOnlyEnabled = ref(false)
 const anthropicPassthroughEnabled = ref(false)
+const webSearchEmulationEnabled = ref(false)
 const mixedScheduling = ref(false) // For antigravity accounts: enable mixed scheduling
 const allowOverages = ref(false) // For antigravity accounts: enable AI Credits overages
 const antigravityAccountType = ref<'oauth' | 'upstream'>('oauth') // For antigravity: oauth or upstream
@@ -3307,6 +3325,7 @@ watch(
     }
     if (newPlatform !== 'anthropic') {
       anthropicPassthroughEnabled.value = false
+      webSearchEmulationEnabled.value = false
     }
     // Reset OAuth states
     oauth.resetState()
@@ -3326,6 +3345,7 @@ watch(
     }
     if (platform !== 'anthropic' || category !== 'apikey') {
       anthropicPassthroughEnabled.value = false
+      webSearchEmulationEnabled.value = false
     }
   }
 )
@@ -3690,6 +3710,7 @@ const resetForm = () => {
   openaiAPIKeyResponsesWebSocketV2Mode.value = OPENAI_WS_MODE_OFF
   codexCLIOnlyEnabled.value = false
   anthropicPassthroughEnabled.value = false
+  webSearchEmulationEnabled.value = false
   // Reset quota control state
   windowCostEnabled.value = false
   windowCostLimit.value = null
@@ -3777,6 +3798,11 @@ const buildAnthropicExtra = (base?: Record<string, unknown>): Record<string, unk
   } else {
     delete extra.anthropic_passthrough
   }
+  if (webSearchEmulationEnabled.value) {
+    extra.web_search_emulation = true
+  } else {
+    delete extra.web_search_emulation
+  }
 
   return Object.keys(extra).length > 0 ? extra : undefined
 }

frontend/src/components/account/EditAccountModal.vue

@@ -1149,10 +1149,61 @@
         </div>
       </div>
 
-      <!-- API Key / Bedrock 账号配额限制 -->
-      <div v-if="account?.type === 'apikey' || account?.type === 'bedrock'" class="border-t border-gray-200 pt-4 dark:border-dark-600 space-y-4">
+      <!-- Anthropic API Key: Web Search Emulation -->
+      <div
+        v-if="account?.platform === 'anthropic' && account?.type === 'apikey'"
+        class="border-t border-gray-200 pt-4 dark:border-dark-600"
+      >
+        <div class="flex items-center justify-between">
+          <div>
+            <label class="input-label mb-0">{{ t('admin.accounts.anthropic.webSearchEmulation') }}</label>
+            <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+              {{ t('admin.accounts.anthropic.webSearchEmulationDesc') }}
+            </p>
+          </div>
+          <Toggle v-model="webSearchEmulationEnabled" />
+        </div>
+      </div>
+
+      <!-- 配额控制 (Anthropic apikey/bedrock: 配额限制 + 亲和) -->
+      <div
+        v-if="account?.platform === 'anthropic' && (account?.type === 'apikey' || account?.type === 'bedrock')"
+        class="border-t border-gray-200 pt-4 dark:border-dark-600 space-y-4"
+      >
         <div class="mb-3">
-          <h3 class="input-label mb-0 text-base font-semibold">{{ t('admin.accounts.quotaLimit') }}</h3>
+          <h3 class="input-label mb-0 text-base font-semibold">{{ t('admin.accounts.quotaControl.title') }}</h3>
+          <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+            {{ t('admin.accounts.quotaControl.hint') }}
+          </p>
+        </div>
+        <QuotaLimitCard
+          :totalLimit="editQuotaLimit"
+          :dailyLimit="editQuotaDailyLimit"
+          :weeklyLimit="editQuotaWeeklyLimit"
+          :dailyResetMode="editDailyResetMode"
+          :dailyResetHour="editDailyResetHour"
+          :weeklyResetMode="editWeeklyResetMode"
+          :weeklyResetDay="editWeeklyResetDay"
+          :weeklyResetHour="editWeeklyResetHour"
+          :resetTimezone="editResetTimezone"
+          @update:totalLimit="editQuotaLimit = $event"
+          @update:dailyLimit="editQuotaDailyLimit = $event"
+          @update:weeklyLimit="editQuotaWeeklyLimit = $event"
+          @update:dailyResetMode="editDailyResetMode = $event"
+          @update:dailyResetHour="editDailyResetHour = $event"
+          @update:weeklyResetMode="editWeeklyResetMode = $event"
+          @update:weeklyResetDay="editWeeklyResetDay = $event"
+          @update:weeklyResetHour="editWeeklyResetHour = $event"
+          @update:resetTimezone="editResetTimezone = $event"
+        />
+      </div>
+      <!-- 配额控制 (非 Anthropic apikey/bedrock) -->
+      <div
+        v-else-if="account?.type === 'apikey' || account?.type === 'bedrock'"
+        class="border-t border-gray-200 pt-4 dark:border-dark-600 space-y-4"
+      >
+        <div class="mb-3">
+          <h3 class="input-label mb-0 text-base font-semibold">{{ t('admin.accounts.quotaControl.title') }}</h3>
           <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
             {{ t('admin.accounts.quotaLimitHint') }}
           </p>
@@ -1237,7 +1288,7 @@
         </div>
       </div>
 
-      <!-- Quota Control Section (Anthropic OAuth/SetupToken only) -->
+      <!-- 配额控制 (Anthropic OAuth/SetupToken: 亲和 + 窗口费用 + 会话 + RPM 等) -->
       <div
         v-if="account?.platform === 'anthropic' && (account?.type === 'oauth' || account?.type === 'setup-token')"
         class="border-t border-gray-200 pt-4 dark:border-dark-600 space-y-4"
@@ -1757,6 +1808,7 @@ import ConfirmDialog from '@/components/common/ConfirmDialog.vue'
 import Select from '@/components/common/Select.vue'
 import Icon from '@/components/icons/Icon.vue'
 import ProxySelector from '@/components/common/ProxySelector.vue'
+import Toggle from '@/components/common/Toggle.vue'
 import GroupSelector from '@/components/common/GroupSelector.vue'
 import ModelWhitelistSelector from '@/components/account/ModelWhitelistSelector.vue'
 import QuotaLimitCard from '@/components/account/QuotaLimitCard.vue'
@@ -1898,6 +1950,7 @@ const openaiOAuthResponsesWebSocketV2Mode = ref<OpenAIWSMode>(OPENAI_WS_MODE_OFF
 const openaiAPIKeyResponsesWebSocketV2Mode = ref<OpenAIWSMode>(OPENAI_WS_MODE_OFF)
 const codexCLIOnlyEnabled = ref(false)
 const anthropicPassthroughEnabled = ref(false)
+const webSearchEmulationEnabled = ref(false)
 const editQuotaLimit = ref<number | null>(null)
 const editQuotaDailyLimit = ref<number | null>(null)
 const editQuotaWeeklyLimit = ref<number | null>(null)
@@ -2067,6 +2120,7 @@ const syncFormFromAccount = (newAccount: Account | null) => {
   openaiAPIKeyResponsesWebSocketV2Mode.value = OPENAI_WS_MODE_OFF
   codexCLIOnlyEnabled.value = false
   anthropicPassthroughEnabled.value = false
+  webSearchEmulationEnabled.value = false
   if (newAccount.platform === 'openai' && (newAccount.type === 'oauth' || newAccount.type === 'apikey')) {
     openaiPassthroughEnabled.value = extra?.openai_passthrough === true || extra?.openai_oauth_passthrough === true
     openaiOAuthResponsesWebSocketV2Mode.value = resolveOpenAIWSModeFromExtra(extra, {
@@ -2087,6 +2141,7 @@ const syncFormFromAccount = (newAccount: Account | null) => {
   }
   if (newAccount.platform === 'anthropic' && newAccount.type === 'apikey') {
     anthropicPassthroughEnabled.value = extra?.anthropic_passthrough === true
+    webSearchEmulationEnabled.value = extra?.web_search_emulation === true
   }
 
   // Load quota limit for apikey/bedrock accounts (bedrock quota is also loaded in its own branch above)
@@ -2522,8 +2577,13 @@ function loadQuotaControlSettings(account: Account) {
   customBaseUrlEnabled.value = false
   customBaseUrl.value = ''
 
-  // Only applies to Anthropic OAuth/SetupToken accounts
-  if (account.platform !== 'anthropic' || (account.type !== 'oauth' && account.type !== 'setup-token')) {
+  // Remaining quota control settings only apply to Anthropic accounts
+  if (account.platform !== 'anthropic') {
+    return
+  }
+
+  // Window cost / session limit only apply to Anthropic OAuth/SetupToken accounts
+  if (account.type !== 'oauth' && account.type !== 'setup-token') {
     return
   }
 
@@ -2949,7 +3009,7 @@ const handleSubmit = async () => {
 
     // For Anthropic OAuth/SetupToken accounts, handle quota control settings in extra
     if (props.account.platform === 'anthropic' && (props.account.type === 'oauth' || props.account.type === 'setup-token')) {
-      const currentExtra = (props.account.extra as Record<string, unknown>) || {}
+      const currentExtra = (updatePayload.extra as Record<string, unknown>) || (props.account.extra as Record<string, unknown>) || {}
       const newExtra: Record<string, unknown> = { ...currentExtra }
 
       // Window cost limit settings
@@ -3037,15 +3097,20 @@ const handleSubmit = async () => {
       updatePayload.extra = newExtra
     }
 
-    // For Anthropic API Key accounts, handle passthrough mode in extra
+    // For Anthropic API Key accounts, handle passthrough mode + web search emulation in extra
     if (props.account.platform === 'anthropic' && props.account.type === 'apikey') {
-      const currentExtra = (props.account.extra as Record<string, unknown>) || {}
+      const currentExtra = (updatePayload.extra as Record<string, unknown>) || (props.account.extra as Record<string, unknown>) || {}
       const newExtra: Record<string, unknown> = { ...currentExtra }
       if (anthropicPassthroughEnabled.value) {
         newExtra.anthropic_passthrough = true
       } else {
         delete newExtra.anthropic_passthrough
       }
+      if (webSearchEmulationEnabled.value) {
+        newExtra.web_search_emulation = true
+      } else {
+        delete newExtra.web_search_emulation
+      }
       updatePayload.extra = newExtra
     }
 
@@ -3089,20 +3154,27 @@ const handleSubmit = async () => {
       const currentExtra = (updatePayload.extra as Record<string, unknown>) ||
         (props.account.extra as Record<string, unknown>) || {}
       const newExtra: Record<string, unknown> = { ...currentExtra }
+      // Total quota
       if (editQuotaLimit.value != null && editQuotaLimit.value > 0) {
         newExtra.quota_limit = editQuotaLimit.value
       } else {
         delete newExtra.quota_limit
       }
+      // Daily quota
       if (editQuotaDailyLimit.value != null && editQuotaDailyLimit.value > 0) {
         newExtra.quota_daily_limit = editQuotaDailyLimit.value
       } else {
         delete newExtra.quota_daily_limit
+        delete newExtra.quota_daily_used
+        delete newExtra.quota_daily_start
       }
+      // Weekly quota
       if (editQuotaWeeklyLimit.value != null && editQuotaWeeklyLimit.value > 0) {
         newExtra.quota_weekly_limit = editQuotaWeeklyLimit.value
       } else {
         delete newExtra.quota_weekly_limit
+        delete newExtra.quota_weekly_used
+        delete newExtra.quota_weekly_start
       }
       // Quota reset mode config
       if (editDailyResetMode.value === 'fixed') {