Extract searchEvents() to EventIndexService, reduce duplication across controllers

- Add searchEvents() method: Meilisearch search with DB fallback
- Use in HomeController, AdminController, AccountController (removes ~45 duplicated lines)
- Add assets/vendor/ to ESLint ignores
- Update EventIndexServiceTest for new constructor

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

tests/Service/EventIndexServiceTest.php

@@ -6,6 +6,7 @@ use App\Entity\Event;
 use App\Entity\User;
 use App\Service\EventIndexService;
 use App\Service\MeilisearchService;
+use Doctrine\ORM\EntityManagerInterface;
 use PHPUnit\Framework\TestCase;
 
 class EventIndexServiceTest extends TestCase
@@ -16,7 +17,8 @@ class EventIndexServiceTest extends TestCase
     protected function setUp(): void
     {
         $this->meilisearch = $this->createMock(MeilisearchService::class);
-        $this->service = new EventIndexService($this->meilisearch);
+        $em = $this->createMock(EntityManagerInterface::class);
+        $this->service = new EventIndexService($this->meilisearch, $em);
     }
 
     private function createEvent(bool $online = true, bool $secret = false): Event