feat(channel-service): add Python FastAPI pywechat channel service

- Add FastAPI project under channel-service/
- Implement mock pywechat client adapter (login, send, heartbeat)
- Add /v1/wechat-personal/login/*, /v1/wechat-personal/send/* APIs
- Add /v1/heartbeat and /v1/monitor/status for client health
- Add /monitor HTML page with Web Components
- Add pytest suite and Dockerfile
- Update .gitignore for Python/Node artifacts

channel-service/app/services/login_service.py

@@ -0,0 +1,53 @@
+from __future__ import annotations
+
+import time
+from typing import Optional
+
+from app.clients.pywechat_client import ClientRegistry, LoginStatus, OnlineStatus, registry
+
+
+class LoginService:
+    def __init__(self, registry: ClientRegistry):
+        self.registry = registry
+
+    def start_login(self, account_id: str, account_name: Optional[str] = None) -> dict:
+        client = self.registry.get_or_create(account_id, account_name)
+        login_id = client.start_login()
+        return {
+            "login_id": login_id,
+            "qr_code_url": client.state.qr_code_url,
+            "status": client.state.login_status.value,
+        }
+
+    def get_status(self, account_id: str) -> dict:
+        client = self.registry.get(account_id)
+        if client is None:
+            return {"found": False, "account_id": account_id}
+        state = client.get_state()
+        return {
+            "found": True,
+            "account_id": state.account_id,
+            "account_name": state.account_name,
+            "login_status": state.login_status.value,
+            "online_status": state.online_status.value,
+            "last_heartbeat_at": state.last_heartbeat_at,
+            "risk_level": state.risk_level,
+            "sent_count_today": state.sent_count_today,
+        }
+
+    def confirm_login(self, account_id: str) -> dict:
+        client = self.registry.get(account_id)
+        if client is None:
+            return {"success": False, "error": "account not found"}
+        client.confirm_login()
+        return {"success": True, "status": client.state.login_status.value}
+
+    def expire_login(self, account_id: str) -> dict:
+        client = self.registry.get(account_id)
+        if client is None:
+            return {"success": False, "error": "account not found"}
+        client.expire_login()
+        return {"success": True, "status": client.state.login_status.value}
+
+
+login_service = LoginService(registry)