feat(app): add frontend url configuration

app/router/redirect.py

@@ -0,0 +1,23 @@
+from __future__ import annotations
+
+import urllib.parse
+
+from app.config import settings
+
+from fastapi import APIRouter, Request
+from fastapi.responses import RedirectResponse
+
+redirect_router = APIRouter(include_in_schema=False)
+
+
+@redirect_router.get("/users/{user_id}")
+@redirect_router.get("/u/{user_id}")
+@redirect_router.get("/b/{beatmap_id}")
+@redirect_router.get("/s/{beatmapset_id}")
+@redirect_router.get("/beatmapsets/{path:path}")
+@redirect_router.get("/multiplayer/rooms/{room_id}")
+async def redirect(request: Request):
+    return RedirectResponse(
+        urllib.parse.urljoin(str(settings.frontend_url), request.url.path),
+        status_code=301,
+    )