feat(清理任务): 引入Ent存储并补充日志与测试

新增 usage_cleanup_task Ent schema 与仓储实现，支持清理任务排序分页
补充清理任务全链路日志、仪表盘重算触发及 UI 过滤调整
完善 repository/service 单测并引入 sqlite 测试依赖

backend/ent/schema/mixins/soft_delete.go

@@ -12,7 +12,6 @@ import (
 	"entgo.io/ent/dialect/sql"
 	"entgo.io/ent/schema/field"
 	"entgo.io/ent/schema/mixin"
-	dbent "github.com/Wei-Shaw/sub2api/ent"
 	"github.com/Wei-Shaw/sub2api/ent/intercept"
 )
 
@@ -113,7 +112,9 @@ func (d SoftDeleteMixin) Hooks() []ent.Hook {
 					SetOp(ent.Op)
 					SetDeletedAt(time.Time)
 					WhereP(...func(*sql.Selector))
-					Client() *dbent.Client
+					Client() interface {
+						Mutate(context.Context, ent.Mutation) (ent.Value, error)
+					}
 				})
 				if !ok {
 					return nil, fmt.Errorf("unexpected mutation type %T", m)

backend/ent/schema/usage_cleanup_task.go

@@ -0,0 +1,75 @@
+package schema
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/Wei-Shaw/sub2api/ent/schema/mixins"
+
+	"entgo.io/ent"
+	"entgo.io/ent/dialect/entsql"
+	"entgo.io/ent/schema"
+	"entgo.io/ent/schema/field"
+	"entgo.io/ent/schema/index"
+)
+
+// UsageCleanupTask 定义使用记录清理任务的 schema。
+type UsageCleanupTask struct {
+	ent.Schema
+}
+
+func (UsageCleanupTask) Annotations() []schema.Annotation {
+	return []schema.Annotation{
+		entsql.Annotation{Table: "usage_cleanup_tasks"},
+	}
+}
+
+func (UsageCleanupTask) Mixin() []ent.Mixin {
+	return []ent.Mixin{
+		mixins.TimeMixin{},
+	}
+}
+
+func (UsageCleanupTask) Fields() []ent.Field {
+	return []ent.Field{
+		field.String("status").
+			MaxLen(20).
+			Validate(validateUsageCleanupStatus),
+		field.JSON("filters", json.RawMessage{}),
+		field.Int64("created_by"),
+		field.Int64("deleted_rows").
+			Default(0),
+		field.String("error_message").
+			Optional().
+			Nillable(),
+		field.Int64("canceled_by").
+			Optional().
+			Nillable(),
+		field.Time("canceled_at").
+			Optional().
+			Nillable(),
+		field.Time("started_at").
+			Optional().
+			Nillable(),
+		field.Time("finished_at").
+			Optional().
+			Nillable(),
+	}
+}
+
+func (UsageCleanupTask) Indexes() []ent.Index {
+	return []ent.Index{
+		index.Fields("status", "created_at"),
+		index.Fields("created_at"),
+		index.Fields("canceled_at"),
+	}
+}
+
+func validateUsageCleanupStatus(status string) error {
+	switch status {
+	case "pending", "running", "succeeded", "failed", "canceled":
+		return nil
+	default:
+		return fmt.Errorf("invalid usage cleanup status: %s", status)
+	}
+}