refactor(caddy): flatten routes to a plain array like bookings

GET /api/caddy/routes now returns the route array directly instead of
{ system, custom }. Frontend state is CaddyRoute[] initialised to [],
rendered with a simple .map() and an empty-state message — mirroring how
bookings are loaded and displayed.

server.ts

@@ -1180,7 +1180,7 @@ async function startServer() {
 
   app.get('/api/caddy/routes', requireAuth, (_req, res) => {
     try {
-      res.json({ system: [], custom: getCaddyRoutes() });
+      res.json(getCaddyRoutes());
     } catch (err: any) {
       res.status(500).json({ error: err.message });
     }