Add authentication features for admin access

- Introduce a new `auth` module with login, logout, and user verification endpoints for a single admin user.
- Update backend routes to require admin authentication for sensitive operations, enhancing security.
- Modify frontend components to include an authentication provider and gate, ensuring only authorized users can access the application.
- Implement a login page for admin access, improving user experience and security management.
- Update API request handling to redirect unauthorized users to the login page, ensuring proper access control.

backend/routes/voice_webrtc.py

@@ -11,9 +11,10 @@
 import asyncio
 
 from db.session import SessionLocal
-from fastapi import APIRouter, WebSocket
+from fastapi import APIRouter, Depends, WebSocket
 from loguru import logger
 from models import AssistantConfig, SignalingOffer
+from services.auth import require_admin, require_admin_websocket
 from services.config_resolver import resolve_runtime_config
 from starlette.websockets import WebSocketDisconnect, WebSocketState
 
@@ -24,7 +25,7 @@ from services.webrtc_ice import aiortc_ice_servers, client_ice_servers
 router = APIRouter(tags=["voice"])
 
 
-@router.get("/api/webrtc/ice-servers")
+@router.get("/api/webrtc/ice-servers", dependencies=[Depends(require_admin)])
 async def ice_servers():
     """Browser fetches STUN/TURN config (with ephemeral TURN creds when configured)."""
     return {"iceServers": client_ice_servers()}
@@ -32,6 +33,8 @@ async def ice_servers():
 
 @router.websocket("/ws/voice")
 async def voice_signaling(websocket: WebSocket):
+    if not await require_admin_websocket(websocket):
+        return
     await websocket.accept()
     peers: dict = {}
     try: