feat(api-key): add independent quota and expiration support

This feature allows API Keys to have their own quota limits and expiration
times, independent of the user's balance.

Backend:
- Add quota, quota_used, expires_at fields to api_key schema
- Implement IsExpired() and IsQuotaExhausted() checks in middleware
- Add ResetQuota and ClearExpiration API endpoints
- Integrate quota billing in gateway handlers (OpenAI, Anthropic, Gemini)
- Include quota/expiration fields in auth cache for performance
- Expiration check returns 403, quota exhausted returns 429

Frontend:
- Add quota and expiration inputs to key create/edit dialog
- Add quick-select buttons for expiration (+7, +30, +90 days)
- Add reset quota confirmation dialog
- Add expires_at column to keys list
- Add i18n translations for new features (en/zh)

Migration:
- Add 045_add_api_key_quota.sql for new columns

frontend/src/api/keys.ts

@@ -44,6 +44,8 @@ export async function getById(id: number): Promise<ApiKey> {
  * @param customKey - Optional custom key value
  * @param ipWhitelist - Optional IP whitelist
  * @param ipBlacklist - Optional IP blacklist
+ * @param quota - Optional quota limit in USD (0 = unlimited)
+ * @param expiresInDays - Optional days until expiry (undefined = never expires)
  * @returns Created API key
  */
 export async function create(
@@ -51,7 +53,9 @@ export async function create(
   groupId?: number | null,
   customKey?: string,
   ipWhitelist?: string[],
-  ipBlacklist?: string[]
+  ipBlacklist?: string[],
+  quota?: number,
+  expiresInDays?: number
 ): Promise<ApiKey> {
   const payload: CreateApiKeyRequest = { name }
   if (groupId !== undefined) {
@@ -66,6 +70,12 @@ export async function create(
   if (ipBlacklist && ipBlacklist.length > 0) {
     payload.ip_blacklist = ipBlacklist
   }
+  if (quota !== undefined && quota > 0) {
+    payload.quota = quota
+  }
+  if (expiresInDays !== undefined && expiresInDays > 0) {
+    payload.expires_in_days = expiresInDays
+  }
 
   const { data } = await apiClient.post<ApiKey>('/keys', payload)
   return data