fix(lint): 修复 openai_gateway_handler 的 staticcheck 问题

backend/internal/handler/openai_gateway_handler.go

@@ -174,10 +174,12 @@ func (h *OpenAIGatewayHandler) Responses(c *gin.Context) {
 				log.Printf("Account wait queue full: account=%d", account.ID)
 				h.handleStreamingAwareError(c, http.StatusTooManyRequests, "rate_limit_error", "Too many pending requests, please retry later", streamStarted)
 				return
-			}
+			} else {
+				// Only set release function if increment succeeded
 				accountWaitRelease = func() {
 					h.concurrencyHelper.DecrementAccountWaitCount(c.Request.Context(), account.ID)
 				}
+			}
 
 			accountReleaseFunc, err = h.concurrencyHelper.AcquireAccountSlotWithWaitTimeout(
 				c,