mo_data: +write_cash_log 函数

cash_log表已存在，新增写入函数便于截图/交易变更时记录现金流水。
用于process_trade.py、手动改cash时调用，保证现金变更可追溯。

知识萃取-盘后 cron 已暂停（莫荷接手知识库报告）

mo_data.py

@@ -185,6 +185,38 @@ def read_watchlist_json():
     return read_watchlist()
 
 
+# ── cash_log 写入 ─────────────────────────────────────────────────────
+
+def write_cash_log(cash_before, cash_after, frozen_before, frozen_after,
+                   source, note, verified=0):
+    """记录现金变更到 cash_log 表。
+
+    参数:
+        cash_before/after   — 变更前后可用现金
+        frozen_before/after — 变更前后冻结资金
+        source              — 'screenshot'/'manual'/'trade'/'import_xls'
+        note                — 备注（如"卖出法拉电子200股"）
+        verified            — 0=未验证 1=Dad已确认
+    返回:
+        log_id (int)
+    """
+    change_amount = round(cash_after - cash_before, 2) if cash_after is not None and cash_before is not None else 0
+    db = sqlite3.connect(DB_PATH)
+    try:
+        cur = db.execute(
+            """INSERT INTO cash_log
+               (timestamp, cash_before, cash_after, frozen_before, frozen_after,
+                change_amount, source, note, verified)
+               VALUES (datetime('now','localtime'), ?, ?, ?, ?, ?, ?, ?, ?)""",
+            (cash_before, cash_after, frozen_before, frozen_after,
+             change_amount, source, note, verified)
+        )
+        db.commit()
+        return cur.lastrowid
+    finally:
+        db.close()
+
+
 # ── 自检 ────────────────────────────────────────────────────────────
 
 if __name__ == "__main__":