feat(strategy): WeChat notify on trend and roll plan start/end

Add shared strategy_wechat_notify helpers; hook trend execute/finalize and roll group open/close across four exchanges and Gate bot.

Co-authored-by: Cursor <cursoragent@cursor.com>

strategy_roll_monitor_lib.py

@@ -72,10 +72,25 @@ def _close_roll_group(
                 "UPDATE roll_legs SET status='cancelled' WHERE id=? AND status='pending'",
                 (ld["id"],),
             )
-    conn.execute(
+    cur = conn.execute(
         "UPDATE roll_groups SET status='closed', updated_at=? WHERE id=? AND status='active'",
         (_now(cfg), gid),
     )
+    if getattr(cur, "rowcount", 0):
+        try:
+            from strategy_wechat_notify import notify_roll_group_ended
+
+            reason = "下单监控已结案或交易所无同向持仓"
+            notify_roll_group_ended(
+                cfg,
+                group_id=gid,
+                symbol=group.get("symbol") or "",
+                direction=group.get("direction") or "long",
+                reason=reason,
+                leg_count=int(group.get("leg_count") or 0),
+            )
+        except Exception:
+            pass
     try:
         from strategy_snapshot_lib import save_roll_group_snapshot