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>

package.json

@@ -11,12 +11,15 @@
     },
     "devDependencies": {
         "@tailwindcss/postcss": "^4.1.18",
+        "eslint": "^10.0.3",
         "idb": "^8.0.3",
         "idb-keyval": "^6.2.2",
         "postcss": "^8.5.6",
         "postcss-scss": "^4.0.9",
         "rollup-plugin-javascript-obfuscator": "^1.0.4",
         "sass": "^1.97.3",
+        "stylelint": "^17.4.0",
+        "stylelint-config-standard-scss": "^17.0.0",
         "vite": "^7.3.1"
     },
     "dependencies": {