fix: resolve Feishu cross-app notification routing bug

Implement per-app open_id storage via user_feishu_open_ids table with
union_id-based cross-app user identification. WS handlers now auto-capture
open_id+union_id and resolve/associate user accounts. Schedule notifications
route through the correct bot's open_id instead of always falling back to 苹果.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/services/feishu_ws_handler.py

@@ -70,6 +70,21 @@ def _get_sender_open_id(data) -> Optional[str]:
         return None
 
 
+def _get_sender_union_id(data) -> Optional[str]:
+    """从 Feishu 消息事件中提取发送者 union_id（跨应用唯一）。"""
+    try:
+        ev = data.event
+        sender = getattr(ev, "sender", None)
+        if not sender:
+            return None
+        sender_id = getattr(sender, "sender_id", None)
+        if not sender_id:
+            return None
+        return getattr(sender_id, "union_id", None)
+    except Exception:
+        return None
+
+
 def _get_chat_type(data) -> str:
     """获取聊天类型。"""
     try:
@@ -103,6 +118,7 @@ def _reply_card(open_id: str, title: str, content: str, status: str = "info"):
 async def _handle_message_async(data):
     """异步处理飞书消息。"""
     open_id = _get_sender_open_id(data)
+    union_id = _get_sender_union_id(data)
     chat_type = _get_chat_type(data)
     text = _get_message_text(data)
 
@@ -128,11 +144,21 @@ async def _handle_message_async(data):
     from app.core.database import SessionLocal
     from app.models.user import User
     from app.models.agent import Agent
+    from app.services.feishu_open_id_service import resolve_user_and_save
 
     db: Optional[Session] = None
     try:
         db = SessionLocal()
+
+        # 自动保存/关联此应用的 open_id（跨应用识别）
+        resolved_uid = resolve_user_and_save(
+            db, app_id=settings.FEISHU_APP_ID or "",
+            open_id=open_id, union_id=union_id,
+        )
+
         user = db.query(User).filter(User.feishu_open_id == open_id).first()
+        if not user and resolved_uid:
+            user = db.query(User).filter(User.id == resolved_uid).first()
         if not user:
             _reply_to_feishu(open_id, "你的账号未绑定平台用户，请先在平台绑定飞书。")
             return