Update static file routing and root endpoint for frontend integration

- Change static file mount point to `/app` with HTML support.
- Replace root endpoint's `FileResponse` with `RedirectResponse` to `/app/`.
- Update server availability check URL in Electron app to align with new routing.

electron-app/main.js

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:b13ad99183c12a3c1cfc580c68b6ef77f599ba39ab59d5ef1257346e07425635
-size 6443
+oid sha256:673ca7b004730c2da12f2d88ea33a5f4d275e91974022ecaa55af9d311352c82
+size 6447

src/voice_dialogue/api/app.py

@@ -3,7 +3,7 @@ from typing import Dict, Any
 
 from fastapi import FastAPI, HTTPException, APIRouter
 from fastapi.middleware.cors import CORSMiddleware
-from fastapi.responses import FileResponse
+from fastapi.responses import RedirectResponse
 from fastapi.staticfiles import StaticFiles
 
 from voice_dialogue.config.paths import FRONTEND_ASSETS_PATH
@@ -51,7 +51,7 @@ def create_app() -> FastAPI:
     _register_exception_handlers(app)
 
     # 添加静态文件路由
-    app.mount("/", StaticFiles(directory=FRONTEND_ASSETS_PATH.as_posix()), name="static")
+    app.mount("/app", StaticFiles(directory=FRONTEND_ASSETS_PATH.as_posix(), html=True), name="static")
 
     return app
 
@@ -76,8 +76,7 @@ def _register_health_routes(app: FastAPI):
 
     @app.get("/")
     async def root():
-        index_file = FRONTEND_ASSETS_PATH / "index.html"
-        return FileResponse(index_file)
+        return RedirectResponse(url='/app/')
 
 
 def _get_service_status(app_state: Dict[str, Any]) -> dict: