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/Controllers/Auth/RegisterController.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace App\Http\Controllers\Auth;
+
+use App\Http\Controllers\Controller;
+use App\Models\User;
+use Illuminate\Foundation\Auth\RegistersUsers;
+use Illuminate\Support\Facades\Hash;
+use Illuminate\Support\Facades\Validator;
+
+class RegisterController extends Controller
+{
+    use RegistersUsers;
+
+    protected $redirectTo = '/';
+
+    public function __construct()
+    {
+        $this->middleware('guest');
+    }
+
+    protected function validator(array $data)
+    {
+        return Validator::make($data, [
+            'name' => ['required', 'string', 'max:255'],
+            'email' => ['required', 'string', 'email', 'max:255', 'unique:users'],
+            'password' => ['required', 'string', 'min:8', 'confirmed'],
+        ]);
+    }
+
+    protected function create(array $data)
+    {
+        return User::create([
+            'name' => $data['name'],
+            'email' => $data['email'],
+            'password' => Hash::make($data['password']),
+        ]);
+    }
+}