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/QrController.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use Illuminate\Http\Request;
+
+class QrController extends Controller
+{
+    public function show($content)
+    {
+        return view('qr.show', compact('content'));
+    }
+
+    public function reGenerate($id, $type)
+    {
+        return redirect()->back();
+    }
+}