feat(api-key): 添加 IP 白名单/黑名单限制功能 (#221)

* feat(api-key): add IP whitelist/blacklist restriction and usage log IP tracking

- Add IP restriction feature for API keys (whitelist/blacklist with CIDR support)
- Add IP address logging to usage logs (admin-only visibility)
- Remove billing_type column from usage logs UI (redundant)
- Use generic "Access denied" error message for security

Backend:
- New ip package with IP/CIDR validation and matching utilities
- Database migrations for ip_whitelist, ip_blacklist (api_keys) and ip_address (usage_logs)
- Middleware IP restriction check after API key validation
- Input validation for IP/CIDR patterns on create/update

Frontend:
- API key form with enable toggle for IP restriction
- Shield icon indicator in table for keys with IP restriction
- Removed billing_type filter and column from usage views

* fix: update API contract tests for ip_whitelist/ip_blacklist fields

Add ip_whitelist and ip_blacklist fields to expected JSON responses
in API contract tests to match the new API key schema.

frontend/src/components/admin/usage/UsageFilters.vue

@@ -127,12 +127,6 @@
           <Select v-model="filters.stream" :options="streamTypeOptions" @change="emitChange" />
         </div>
 
-        <!-- Billing Type Filter -->
-        <div class="w-full sm:w-auto sm:min-w-[180px]">
-          <label class="input-label">{{ t('usage.billingType') }}</label>
-          <Select v-model="filters.billing_type" :options="billingTypeOptions" @change="emitChange" />
-        </div>
-
         <!-- Group Filter -->
         <div class="w-full sm:w-auto sm:min-w-[200px]">
           <label class="input-label">{{ t('admin.usage.group') }}</label>
@@ -227,12 +221,6 @@ const streamTypeOptions = ref<SelectOption[]>([
   { value: false, label: t('usage.sync') }
 ])
 
-const billingTypeOptions = ref<SelectOption[]>([
-  { value: null, label: t('admin.usage.allBillingTypes') },
-  { value: 1, label: t('usage.subscription') },
-  { value: 0, label: t('usage.balance') }
-])
-
 const emitChange = () => emit('change')
 
 const updateStartDate = (value: string) => {

frontend/src/components/admin/usage/UsageTable.vue

@@ -96,12 +96,6 @@
           </div>
         </template>
 
-        <template #cell-billing_type="{ row }">
-          <span class="inline-flex items-center rounded px-2 py-0.5 text-xs font-medium" :class="row.billing_type === 1 ? 'bg-purple-100 text-purple-800 dark:bg-purple-900 dark:text-purple-200' : 'bg-emerald-100 text-emerald-800 dark:bg-emerald-900 dark:text-emerald-200'">
-            {{ row.billing_type === 1 ? t('usage.subscription') : t('usage.balance') }}
-          </span>
-        </template>
-
         <template #cell-first_token="{ row }">
           <span v-if="row.first_token_ms != null" class="text-sm text-gray-600 dark:text-gray-400">{{ formatDuration(row.first_token_ms) }}</span>
           <span v-else class="text-sm text-gray-400 dark:text-gray-500">-</span>
@@ -120,6 +114,11 @@
           <span v-else class="text-sm text-gray-400 dark:text-gray-500">-</span>
         </template>
 
+        <template #cell-ip_address="{ row }">
+          <span v-if="row.ip_address" class="text-sm font-mono text-gray-600 dark:text-gray-400">{{ row.ip_address }}</span>
+          <span v-else class="text-sm text-gray-400 dark:text-gray-500">-</span>
+        </template>
+
         <template #empty><EmptyState :message="t('usage.noRecords')" /></template>
       </DataTable>
     </div>
@@ -249,11 +248,11 @@ const cols = computed(() => [
   { key: 'stream', label: t('usage.type'), sortable: false },
   { key: 'tokens', label: t('usage.tokens'), sortable: false },
   { key: 'cost', label: t('usage.cost'), sortable: false },
-  { key: 'billing_type', label: t('usage.billingType'), sortable: false },
   { key: 'first_token', label: t('usage.firstToken'), sortable: false },
   { key: 'duration', label: t('usage.duration'), sortable: false },
   { key: 'created_at', label: t('usage.time'), sortable: true },
-  { key: 'user_agent', label: t('usage.userAgent'), sortable: false }
+  { key: 'user_agent', label: t('usage.userAgent'), sortable: false },
+  { key: 'ip_address', label: t('admin.usage.ipAddress'), sortable: false }
 ])
 
 const formatCacheTokens = (tokens: number): string => {