Merge pull request #486 from s-Joshua-s/feat/usage-filter-by-apikey

feat(gateway): filter /v1/usage stats by API Key instead of UserID

backend/internal/handler/gateway_handler.go

@@ -616,10 +616,10 @@ func (h *GatewayHandler) Usage(c *gin.Context) {
 		return
 	}
 
-	// Best-effort: 获取用量统计，失败不影响基础响应
+	// Best-effort: 获取用量统计（按当前 API Key 过滤），失败不影响基础响应
 	var usageData gin.H
 	if h.usageService != nil {
-		dashStats, err := h.usageService.GetUserDashboardStats(c.Request.Context(), subject.UserID)
+		dashStats, err := h.usageService.GetAPIKeyDashboardStats(c.Request.Context(), apiKey.ID)
 		if err == nil && dashStats != nil {
 			usageData = gin.H{
 				"today": gin.H{