Add CI pipeline, Meilisearch service, CacheService and code quality tools

- CI: lint, PHPStan, PHP CS Fixer, ESLint, Stylelint, security audit, build
- MeilisearchService: async via Messenger, sync search
- MeilisearchMessage + handler for async operations
- CacheService with CacheKey enum (TTL per key, remember pattern)
- Meilisearch env vars in .env.local, vault and env.local.j2
- Messenger routing for MeilisearchMessage
- PHPStan level 6, ESLint, Stylelint configs

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

.php-cs-fixer.dist.php

@@ -0,0 +1,17 @@
+<?php
+
+$finder = (new PhpCsFixer\Finder())
+    ->in(__DIR__)
+    ->exclude('var')
+    ->notPath([
+        'config/bundles.php',
+        'config/reference.php',
+    ])
+;
+
+return (new PhpCsFixer\Config())
+    ->setRules([
+        '@Symfony' => true,
+    ])
+    ->setFinder($finder)
+;