remove inertia backend adapter

Remove the adapter dependency, middleware, configuration, and frontend route. Leave the backend root unclaimed so the standalone Vue application remains independent.

backend/bootstrap/app.php

@@ -1,6 +1,5 @@
 <?php
 
-use App\Http\Middleware\HandleInertiaRequests;
 use Illuminate\Foundation\Application;
 use Illuminate\Foundation\Configuration\Exceptions;
 use Illuminate\Foundation\Configuration\Middleware;
@@ -15,7 +14,6 @@ return Application::configure(basePath: dirname(__DIR__))
     )
     ->withMiddleware(function (Middleware $middleware): void {
         $middleware->web(append: [
-            HandleInertiaRequests::class,
             AddLinkHeadersForPreloadedAssets::class,
         ]);
     })