Replace mounted fastapi-admin with plain FastAPI admin router

app/main.py

@@ -15,9 +15,12 @@ from typing import AsyncGenerator
 
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
-from starlette.responses import RedirectResponse
-from starlette.status import HTTP_303_SEE_OTHER
 
+from app.admin_web import (
+    configure_admin_web,
+    router as admin_web_router,
+    shutdown_admin_web,
+)
 from app.core.config import get_settings
 from app.database import close_db, init_db
 from app.routers import (
@@ -43,17 +46,13 @@ async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
     # Startup: Initialize database
     await init_db()
     if settings.ENABLE_ADMIN:
-        from app.admin import configure_admin_app
-
-        await configure_admin_app()
+        await configure_admin_web()
     
     yield
     
     # Shutdown: Close database connections
     if settings.ENABLE_ADMIN:
-        from app.admin import shutdown_admin_app
-
-        await shutdown_admin_app()
+        await shutdown_admin_web()
     await close_db()
 
 
@@ -177,21 +176,12 @@ app.include_router(
 )
 
 if settings.ENABLE_ADMIN:
-    from app.admin import admin as admin_app
-
-    @app.get("/admin", include_in_schema=False)
-    async def admin_entrypoint():
-        # Avoid Starlette mount slash-normalization redirect, which can emit an
-        # absolute URL based on proxy headers such as https://127.0.0.1/admin/.
-        return RedirectResponse(url="/admin/", status_code=HTTP_303_SEE_OTHER)
-
     app.include_router(
         ai_router,
         prefix=f"{settings.API_V1_STR}",
     )
 
-    # Mount FastAPI Admin panel
-    app.mount("/admin", admin_app)
+    app.include_router(admin_web_router)
 
     # Include admin API router for custom actions
     app.include_router(