Add PWA scanner app for organizers at /scanner

Standalone installable PWA with:
- JWT login via /api/auth/login
- Event list from /api/live/events
- QR code camera scanning (html5-qrcode library)
- Scan results with accepted/refused state and ticket details
- Auto token refresh on expiry
- Offline caching via service worker
- Dark theme optimized for outdoor scanning
- Vibration feedback on scan

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/Controller/ScannerControllerTest.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace App\Tests\Controller;
+
+use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+
+class ScannerControllerTest extends WebTestCase
+{
+    public function testScannerPageReturnsSuccess(): void
+    {
+        $client = static::createClient();
+        $client->request('GET', '/scanner');
+
+        self::assertResponseIsSuccessful();
+        self::assertSelectorTextContains('title', 'E-Ticket Scanner');
+    }
+
+    public function testScannerManifestReturnsJson(): void
+    {
+        $client = static::createClient();
+        $client->request('GET', '/scanner/manifest.json');
+
+        self::assertResponseIsSuccessful();
+        self::assertResponseHeaderSame('Content-Type', 'application/manifest+json');
+
+        $data = json_decode($client->getResponse()->getContent(), true);
+        self::assertSame('E-Ticket Scanner', $data['name']);
+        self::assertSame('standalone', $data['display']);
+        self::assertSame('/scanner', $data['start_url']);
+    }
+
+    public function testScannerPageIsAccessibleWithoutAuth(): void
+    {
+        $client = static::createClient();
+        $client->request('GET', '/scanner');
+
+        self::assertResponseIsSuccessful();
+        self::assertResponseStatusCodeSame(200);
+    }
+}