Add missing app files and fix Docker configuration

- Add all PHP app files (controllers, middleware, providers, models, enums)
  that were previously gitignored via app/.gitignore wildcard
- Fix app/.gitignore to no longer ignore all files
- Fix docker-compose.yml: use named volume for postgres to avoid chown permission errors on server
- Fix Dockerfile: use --classmap-authoritative for composer dump-autoload

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Http/Middleware/RedirectIfAuthenticated.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use App\Providers\RouteServiceProvider;
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Auth;
+
+class RedirectIfAuthenticated
+{
+    public function handle(Request $request, Closure $next, string ...$guards): mixed
+    {
+        $guards = empty($guards) ? [null] : $guards;
+
+        foreach ($guards as $guard) {
+            if (Auth::guard($guard)->check()) {
+                return redirect(RouteServiceProvider::HOME);
+            }
+        }
+
+        return $next($request);
+    }
+}