Merge PR #73: feat(antigravity): 添加 Antigravity (Cloud AI Companion) 平台支持

新增功能:
- Antigravity OAuth 授权流程支持
- Claude → Gemini 协议转换（Claude API 请求自动转换为 Gemini 格式）
- 配额刷新和状态显示
- 混合调度功能，支持 Anthropic 和 Antigravity 账户混合使用
- /antigravity 专用路由，支持仅使用 Antigravity 账户
- 前端 Antigravity 服务商标识和账户管理功能

冲突解决:
- CreateAccountModal.vue: 合并 data-tour 属性和 mixed-scheduling 属性
- EditAccountModal.vue: 合并 data-tour 属性和 mixed-scheduling 属性

代码质量改进:
- 修复 antigravity 类型文件的 gofmt 格式问题（struct 字段对齐、interface{} → any）
- 移除 .golangci.yml 中的 gofmt 排除规则
- 修复测试文件的格式问题

frontend/src/components/account/EditAccountModal.vue

@@ -472,11 +472,47 @@
         <Select v-model="form.status" :options="statusOptions" />
       </div>
 
-      <!-- Group Selection - 仅标准模式显示 -->
-      <div v-if="!authStore.isSimpleMode" data-tour="account-form-groups">
-        <GroupSelector v-model="form.group_ids" :groups="groups" :platform="account?.platform" />
+      <!-- Mixed Scheduling (only for antigravity accounts, read-only in edit mode) -->
+      <div v-if="account?.platform === 'antigravity'" class="flex items-center gap-2">
+        <label class="flex cursor-not-allowed items-center gap-2 opacity-60">
+          <input
+            type="checkbox"
+            v-model="mixedScheduling"
+            disabled
+            class="h-4 w-4 cursor-not-allowed rounded border-gray-300 text-primary-500 focus:ring-primary-500 dark:border-dark-500"
+          />
+          <span class="text-sm font-medium text-gray-700 dark:text-gray-300">
+            {{ t('admin.accounts.mixedScheduling') }}
+          </span>
+        </label>
+        <div class="group relative">
+          <span
+            class="inline-flex h-4 w-4 cursor-help items-center justify-center rounded-full bg-gray-200 text-xs text-gray-500 hover:bg-gray-300 dark:bg-dark-600 dark:text-gray-400 dark:hover:bg-dark-500"
+          >
+            ?
+          </span>
+          <!-- Tooltip（向下显示避免被弹窗裁剪） -->
+          <div
+            class="pointer-events-none absolute left-0 top-full z-[100] mt-1.5 w-72 rounded bg-gray-900 px-3 py-2 text-xs text-white opacity-0 transition-opacity group-hover:opacity-100 dark:bg-gray-700"
+          >
+            {{ t('admin.accounts.mixedSchedulingTooltip') }}
+            <div
+              class="absolute bottom-full left-3 border-4 border-transparent border-b-gray-900 dark:border-b-gray-700"
+            ></div>
+          </div>
+        </div>
       </div>
 
+      <!-- Group Selection - 仅标准模式显示 -->
+      <GroupSelector
+        v-if="!authStore.isSimpleMode"
+        v-model="form.group_ids"
+        :groups="groups"
+        :platform="account?.platform"
+        :mixed-scheduling="mixedScheduling"
+        data-tour="account-form-groups"
+      />
+
     </form>
 
     <template #footer>
@@ -572,6 +608,7 @@ const customErrorCodesEnabled = ref(false)
 const selectedErrorCodes = ref<number[]>([])
 const customErrorCodeInput = ref<number | null>(null)
 const interceptWarmupRequests = ref(false)
+const mixedScheduling = ref(false) // For antigravity accounts: enable mixed scheduling
 
 // Common models for whitelist - Anthropic
 const anthropicModels = [
@@ -783,6 +820,10 @@ watch(
       const credentials = newAccount.credentials as Record<string, unknown> | undefined
       interceptWarmupRequests.value = credentials?.intercept_warmup_requests === true
 
+      // Load mixed scheduling setting (only for antigravity accounts)
+      const extra = newAccount.extra as Record<string, unknown> | undefined
+      mixedScheduling.value = extra?.mixed_scheduling === true
+
       // Initialize API Key fields for apikey type
       if (newAccount.type === 'apikey' && newAccount.credentials) {
         const credentials = newAccount.credentials as Record<string, unknown>
@@ -988,6 +1029,18 @@ const handleSubmit = async () => {
       updatePayload.credentials = newCredentials
     }
 
+    // For antigravity accounts, handle mixed_scheduling in extra
+    if (props.account.platform === 'antigravity') {
+      const currentExtra = (props.account.extra as Record<string, unknown>) || {}
+      const newExtra: Record<string, unknown> = { ...currentExtra }
+      if (mixedScheduling.value) {
+        newExtra.mixed_scheduling = true
+      } else {
+        delete newExtra.mixed_scheduling
+      }
+      updatePayload.extra = newExtra
+    }
+
     await adminAPI.accounts.update(props.account.id, updatePayload)
     appStore.showSuccess(t('admin.accounts.accountUpdated'))
     emit('updated')