fix(gateway): 自定义错误码触发停止调度

- 修改 HandleUpstreamError 逻辑，启用自定义错误码时所有在列表中的错误码都会停止调度
- 添加 handleCustomErrorCode 函数处理自定义错误码的账号停用
- 前端添加 429/529 错误码的警告提示，因为这些错误码已有内置处理机制
- 更新 EditAccountModal、CreateAccountModal、BulkEditAccountModal 的错误码添加逻辑

backend/internal/service/ratelimit_service.go

@@ -49,6 +49,7 @@ func NewRateLimitService(accountRepo AccountRepository, usageRepo UsageLogReposi
 func (s *RateLimitService) HandleUpstreamError(ctx context.Context, account *Account, statusCode int, headers http.Header, responseBody []byte) (shouldDisable bool) {
 	// apikey 类型账号：检查自定义错误码配置
 	// 如果启用且错误码不在列表中，则不处理（不停止调度、不标记限流/过载）
+	customErrorCodesEnabled := account.IsCustomErrorCodesEnabled()
 	if !account.ShouldHandleErrorCode(statusCode) {
 		log.Printf("Account %d: error %d skipped (not in custom error codes)", account.ID, statusCode)
 		return false
@@ -93,11 +94,19 @@ func (s *RateLimitService) HandleUpstreamError(ctx context.Context, account *Acc
 		s.handle529(ctx, account)
 		shouldDisable = false
 	default:
-		// 其他5xx错误：记录但不停止调度
-		if statusCode >= 500 {
+		// 自定义错误码启用时：在列表中的错误码都应该停止调度
+		if customErrorCodesEnabled {
+			msg := "Custom error code triggered"
+			if upstreamMsg != "" {
+				msg = upstreamMsg
+			}
+			s.handleCustomErrorCode(ctx, account, statusCode, msg)
+			shouldDisable = true
+		} else if statusCode >= 500 {
+			// 未启用自定义错误码时：仅记录5xx错误
 			log.Printf("Account %d received upstream error %d", account.ID, statusCode)
+			shouldDisable = false
 		}
-		shouldDisable = false
 	}
 
 	if tempMatched {
@@ -273,6 +282,16 @@ func (s *RateLimitService) handleAuthError(ctx context.Context, account *Account
 	log.Printf("Account %d disabled due to auth error: %s", account.ID, errorMsg)
 }
 
+// handleCustomErrorCode 处理自定义错误码，停止账号调度
+func (s *RateLimitService) handleCustomErrorCode(ctx context.Context, account *Account, statusCode int, errorMsg string) {
+	msg := "Custom error code " + strconv.Itoa(statusCode) + ": " + errorMsg
+	if err := s.accountRepo.SetError(ctx, account.ID, msg); err != nil {
+		log.Printf("SetError failed for account %d: %v", account.ID, err)
+		return
+	}
+	log.Printf("Account %d disabled due to custom error code %d: %s", account.ID, statusCode, errorMsg)
+}
+
 // handle429 处理429限流错误
 // 解析响应头获取重置时间，标记账号为限流状态
 func (s *RateLimitService) handle429(ctx context.Context, account *Account, headers http.Header) {