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

backend/internal/server/middleware/api_key_auth.go

@@ -70,7 +70,27 @@ func apiKeyAuthWithSubscription(apiKeyService *service.APIKeyService, subscripti
 
 		// 检查API key是否激活
 		if !apiKey.IsActive() {
-			AbortWithError(c, 401, "API_KEY_DISABLED", "API key is disabled")
+			// Provide more specific error message based on status
+			switch apiKey.Status {
+			case service.StatusAPIKeyQuotaExhausted:
+				AbortWithError(c, 429, "API_KEY_QUOTA_EXHAUSTED", "API key 额度已用完")
+			case service.StatusAPIKeyExpired:
+				AbortWithError(c, 403, "API_KEY_EXPIRED", "API key 已过期")
+			default:
+				AbortWithError(c, 401, "API_KEY_DISABLED", "API key is disabled")
+			}
+			return
+		}
+
+		// 检查API Key是否过期（即使状态是active，也要检查时间）
+		if apiKey.IsExpired() {
+			AbortWithError(c, 403, "API_KEY_EXPIRED", "API key 已过期")
+			return
+		}
+
+		// 检查API Key配额是否耗尽
+		if apiKey.IsQuotaExhausted() {
+			AbortWithError(c, 429, "API_KEY_QUOTA_EXHAUSTED", "API key 额度已用完")
 			return
 		}