Phase 2: ProxyService reverse proxy (HTTP+WebSocket forwarding)

- New: services/proxy_service.py (path->URL mapping)
- New: services/web_panel/routes/proxy.py (3 REST endpoints)
- New: static/web_panel/pages/proxy.html (WebUI)
- Tests: 28/28 passing

services/web_panel/manager.py

@@ -5,7 +5,7 @@ import os
 import logging
 from pathlib import Path
 from aiohttp import web
-from .routes import auth, status, plugins, commands, logs, projects
+from .routes import auth, status, plugins, commands, logs, projects, proxy
 
 logger = logging.getLogger(__name__)
 
@@ -63,6 +63,7 @@ class WebPanelManager:
         commands.setup_routes(app, self.base_path)
         logs.setup_routes(app, self.base_path)
         projects.setup_project_routes(app, self.sm)
+        proxy.setup_proxy_routes(app, self.sm)
         
         # 注册日志广播
         ls = self.sm.get_service("log")