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>

.gitignore

@@ -16,3 +16,8 @@
 node_modules/
 .idea/
 cert/
+
+###> friendsofphp/php-cs-fixer ###
+/.php-cs-fixer.php
+/.php-cs-fixer.cache
+###< friendsofphp/php-cs-fixer ###