feat(context): 接入 IndicatorUsecase，填实 Technical 字段

- MarketContextUsecase 增 IndicatorComputer 字段；构造器增参
- 用既有常量 derivativePeriod ("1h") 作为指标计算的 primary interval
  —— 与 LSR 采样时基对齐；未来切换 primary 改一个常量即可
- 替换原 hard-coded 空 Technical（market_context.go l.186-189）
- app.go 注入 usecase.NewIndicatorUsecase()

端到端 smoke 留给 commit 7 在所有测试就位后做（make docker-up + migrate-up + run）。

internal/usecase/market_context.go

@@ -39,6 +39,8 @@ type MarketContextUsecase struct {
 	oiRepo      OpenInterestRepository
 	lsRepo      LongShortRatioRepository
 
+	indicator IndicatorComputer
+
 	log *slog.Logger
 }
 
@@ -49,6 +51,7 @@ func NewMarketContextUsecase(
 	fundingRepo FundingRepository,
 	oiRepo OpenInterestRepository,
 	lsRepo LongShortRatioRepository,
+	indicator IndicatorComputer,
 	log *slog.Logger,
 ) *MarketContextUsecase {
 	return &MarketContextUsecase{
@@ -58,6 +61,7 @@ func NewMarketContextUsecase(
 		fundingRepo: fundingRepo,
 		oiRepo:      oiRepo,
 		lsRepo:      lsRepo,
+		indicator:   indicator,
 		log:         log,
 	}
 }
@@ -183,10 +187,7 @@ func (u *MarketContextUsecase) Build(ctx context.Context, symbol string) (*entit
 			},
 			TakerBuySellVolume: nil,
 		},
-		Technical: entity.TechnicalStructure{
-			Support:    []entity.TechnicalLevel{},
-			Resistance: []entity.TechnicalLevel{},
-		},
+		Technical: u.indicator.Compute(klines[derivativePeriod], globalLS),
 		DataQuality: entity.DataQuality{
 			Source:   "binance",
 			Warnings: warnings,