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>

db/db.go

@@ -150,6 +150,24 @@ func (d *DB) migrate() error {
 	);
 	CREATE INDEX IF NOT EXISTS idx_cm_events_coin   ON cm_events(coin);
 	CREATE INDEX IF NOT EXISTS idx_cm_events_created ON cm_events(created_at);
+
+	CREATE TABLE IF NOT EXISTS trend_signals (
+		id           INTEGER PRIMARY KEY AUTOINCREMENT,
+		coin         TEXT NOT NULL,
+		type         TEXT NOT NULL,
+		signal_score REAL,
+		price        REAL,
+		ema_52       REAL,
+		ema_slope    REAL,
+		volume_ratio REAL,
+		range_24h    REAL,
+		vol_baseline REAL,
+		price_above_ema INTEGER,
+		state        TEXT,
+		created_at   DATETIME NOT NULL
+	);
+	CREATE INDEX IF NOT EXISTS idx_trend_signals_coin ON trend_signals(coin);
+	CREATE INDEX IF NOT EXISTS idx_trend_signals_created ON trend_signals(created_at);
 	`
 	_, err := d.Exec(schema)
 	if err != nil {

db/trend_signal.go

@@ -0,0 +1,64 @@
+package db
+
+import "time"
+
+// TrendSignalRecord mirrors the trend_signals table row.
+type TrendSignalRecord struct {
+	ID            int64
+	Coin          string
+	Type          string // "enter" or "exit"
+	SignalScore   *float64
+	Price         *float64
+	EMA52         *float64
+	EMASlope      *float64
+	VolumeRatio   *float64
+	Range24h      *float64
+	VolBaseline   *float64
+	PriceAboveEMA bool
+	State         *string
+	CreatedAt     time.Time
+}
+
+// SaveTrendSignal inserts a new trend signal record.
+func (d *DB) SaveTrendSignal(s *TrendSignalRecord) (int64, error) {
+	pa := 0
+	if s.PriceAboveEMA {
+		pa = 1
+	}
+	res, err := d.Exec(`INSERT INTO trend_signals
+		(coin, type, signal_score, price, ema_52, ema_slope, volume_ratio,
+		 range_24h, vol_baseline, price_above_ema, state, created_at)
+		VALUES (?,?,?,?,?,?,?,?,?,?,?,?)`,
+		s.Coin, s.Type, s.SignalScore, s.Price, s.EMA52, s.EMASlope, s.VolumeRatio,
+		s.Range24h, s.VolBaseline, pa, s.State, s.CreatedAt,
+	)
+	if err != nil {
+		return 0, err
+	}
+	return res.LastInsertId()
+}
+
+// GetTrendSignals returns the most recent N trend signal records.
+func (d *DB) GetTrendSignals(limit int) ([]TrendSignalRecord, error) {
+	rows, err := d.Query(`SELECT id, coin, type, signal_score, price, ema_52, ema_slope,
+		volume_ratio, range_24h, vol_baseline, price_above_ema, state, created_at
+		FROM trend_signals ORDER BY id DESC LIMIT ?`, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var signals []TrendSignalRecord
+	for rows.Next() {
+		var s TrendSignalRecord
+		var pa int
+		if err := rows.Scan(&s.ID, &s.Coin, &s.Type, &s.SignalScore, &s.Price,
+			&s.EMA52, &s.EMASlope, &s.VolumeRatio, &s.Range24h, &s.VolBaseline,
+			&pa, &s.State, &s.CreatedAt); err != nil {
+			return nil, err
+		}
+		s.PriceAboveEMA = pa == 1
+		signals = append(signals, s)
+	}
+	return signals, rows.Err()
+}