feat: 限速状态可视化 - 后台订阅详情展示实际限速与降速状态

- 新增 pkg/speedlimit/calculator.go 公共限速计算函数
- UserSubscribeDetail 响应新增 effective_speed/is_throttled/throttle_rule 字段
- GetUserSubscribeById 接口查询时实时计算并返回限速状态
- 重构 getServerUserListLogic 的 calculateEffectiveSpeedLimit，改用共享函数

Co-Authored-By: claude-flow <ruv@ruv.net>

internal/logic/admin/user/getUserSubscribeByIdLogic.go

@@ -6,6 +6,7 @@ import (
 	"github.com/perfect-panel/server/internal/svc"
 	"github.com/perfect-panel/server/internal/types"
 	"github.com/perfect-panel/server/pkg/logger"
+	"github.com/perfect-panel/server/pkg/speedlimit"
 	"github.com/perfect-panel/server/pkg/tool"
 	"github.com/perfect-panel/server/pkg/xerr"
 	"github.com/pkg/errors"
@@ -34,5 +35,14 @@ func (l *GetUserSubscribeByIdLogic) GetUserSubscribeById(req *types.GetUserSubsc
 	}
 	var subscribeDetails types.UserSubscribeDetail
 	tool.DeepCopy(&subscribeDetails, sub)
+
+	// Calculate speed limit status
+	if sub.Subscribe != nil && sub.Status == 1 {
+		result := speedlimit.Calculate(l.ctx, l.svcCtx.DB, sub.UserId, sub.Id, sub.Subscribe.SpeedLimit, sub.Subscribe.TrafficLimit)
+		subscribeDetails.EffectiveSpeed = result.EffectiveSpeed
+		subscribeDetails.IsThrottled = result.IsThrottled
+		subscribeDetails.ThrottleRule = result.ThrottleRule
+	}
+
 	return &subscribeDetails, nil
 }