Add Redis cache for Meilisearch search results and admin dashboard stats

- Configure Redis DB 2 as Symfony cache adapter
- Cache Meilisearch search results for 5 minutes (invalidated on writes)
- Cache admin dashboard stats for 10 minutes
- Add invalidateSearchCache() called after each Meilisearch write
- Update tests to support cache mock injection

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

tests/Service/MeilisearchServiceTest.php

@@ -7,6 +7,8 @@ use App\Service\MeilisearchService;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Messenger\Envelope;
 use Symfony\Component\Messenger\MessageBusInterface;
+use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\ItemInterface;
 use Symfony\Contracts\HttpClient\HttpClientInterface;
 use Symfony\Contracts\HttpClient\ResponseInterface;
 
@@ -14,17 +16,21 @@ class MeilisearchServiceTest extends TestCase
 {
     private HttpClientInterface $httpClient;
     private MessageBusInterface $bus;
+    private CacheInterface $cache;
     private MeilisearchService $service;
 
     protected function setUp(): void
     {
         $this->httpClient = $this->createMock(HttpClientInterface::class);
         $this->bus = $this->createMock(MessageBusInterface::class);
+        $this->cache = $this->createMock(CacheInterface::class);
+        $this->cache->method('get')->willReturnCallback(fn (string $key, callable $callback) => $callback($this->createMock(ItemInterface::class)));
         $this->service = new MeilisearchService(
             $this->httpClient,
             $this->bus,
             'http://meilisearch:7700',
             'test-key',
+            $this->cache,
         );
     }