xiaoguo_scanner: 小果独立扫描线，5分钟一轮，三榜交叉发现

mofin_db.py

@@ -321,9 +321,24 @@ def init_all_tables(conn: sqlite3.Connection):
             created_at      TEXT DEFAULT (datetime('now','localtime'))
         );
         CREATE INDEX IF NOT EXISTS idx_signal_news_signal ON signal_news(signal_id);
+
+        -- 小果扫描跟踪（去重用）
+        CREATE TABLE IF NOT EXISTS xiaoguo_scan_tracker (
+            code            TEXT PRIMARY KEY,
+            name            TEXT,
+            last_scanned_at TEXT,
+            found_count     INTEGER DEFAULT 0
+        );
     """)
     conn.commit()
 
+    # 迁移：给 signal_news 加 source 字段（幂等）
+    try:
+        conn.execute("ALTER TABLE signal_news ADD COLUMN source TEXT DEFAULT 'trend'")
+    except sqlite3.OperationalError:
+        pass
+    conn.commit()
+
 
 # ═══════════════════════════════════════════════════════════
 # 市场快照写入