scheduler: auto-detect new signals once per day, deduplicate existing

- scheduler tick runs detect after fetch+score (once per UTC day)
- ChanSignalDetector skips already-recorded signals
- Prevents duplicate signal_features entries on repeated runs

ChanMacro/chan_integration.py

@@ -145,10 +145,26 @@ class ChanSignalDetector:
             logger.warning("未检测到任何 BSP 信号")
             return 0
 
-        # Step 2: 写入 signal_features（含市场状态和 forward outcomes）
+        # Step 2: 去重 — 跳过已存在的信号
+        from database import get_connection
+        conn = get_connection()
+        existing = set()
+        for row in conn.execute(
+            "SELECT date, signal_type FROM signal_features"
+        ).fetchall():
+            existing.add((row[0], row[1]))
+        conn.close()
+
+        new_signals = [s for s in signals
+                       if (str(s["date"]), s["signal_type"]) not in existing]
+        if not new_signals:
+            logger.info("所有信号已存在，跳过")
+            return 0
+
+        # Step 3: 写入 signal_features
         from expectancy.tracker import SignalTracker
         tracker = SignalTracker()
-        count = tracker.backfill_signals(signals)
+        count = tracker.backfill_signals(new_signals)
 
         logger.info(f"信号入库完成: {count}/{len(signals)}")
         return count