feat: 趋势过滤信号记录系统 + 实时涨跌方向判断

- 新增 TrendFilter 信号记录（enter/exit），按完整信号和高分信号两档分类
- 信号持久化到 data/trend_signals_cache.json，开机自动恢复
- 新增 /api/trend-signals API + SSE trend_signal 实时广播
- 前端新增完整信号卡片和高分信号卡片，移除旧趋势检测卡片
- 评分加入 1h 涨跌方向和实时 drift 惩罚，下跌币不触发信号
- OKX 交易所支持（累积变动、动量、趋势检测）
- 修复 trend_filter.go 编译错误

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

main.go

@@ -75,6 +75,11 @@ func main() {
 	cumulativeTracker := NewCumulativeTracker()
 	log.Printf("[CM] Cumulative change tracking enabled (1m >= %.1f%%, 3+ exchanges)", cumulativeTracker.surgePct1m)
 
+	// Initialize trend filter (Binance K-line based quiet + EMA52 filter)
+	trendFilter := NewTrendFilter(store, trendDetector)
+	trendFilter.Start()
+	defer trendFilter.Stop()
+
 	// Initialize SQLite database
 	database, err := db.Open("")
 	if err != nil {
@@ -90,7 +95,7 @@ func main() {
 	trader.startIPCServer()
 
 	// Initialize dashboard (web server + SSE)
-	dashboard := NewDashboard(store, trader, database, ":8888", cfg, momentumTracker, trendDetector, cumulativeTracker)
+	dashboard := NewDashboard(store, trader, database, ":8888", cfg, momentumTracker, trendDetector, cumulativeTracker, trendFilter)
 	go dashboard.Run()
 
 	// Spread window tracker — measures how long spreads stay above threshold