Fix frontend staging healthcheck for locale redirect

Accept 2xx/3xx on / so next-intl redirect to /en no longer marks the
container unhealthy and blocks nginx from starting.

Co-authored-by: Cursor <cursoragent@cursor.com>

infrastructure/docker-compose.staging.yml

@@ -77,7 +77,8 @@ services:
       - dyolink_staging
     restart: unless-stopped
     healthcheck:
-      test: ["CMD", "node", "-e", "require('http').get('http://127.0.0.1:3000/', (r) => {if(r.statusCode!==200)process.exit(1)})"]
+      # Root redirects to /en (next-intl) — accept 2xx/3xx as healthy.
+      test: ["CMD", "node", "-e", "require('http').get('http://127.0.0.1:3000/', (r) => { process.exit(r.statusCode >= 200 && r.statusCode < 400 ? 0 : 1); }).on('error', () => process.exit(1))"]
       interval: 30s
       timeout: 10s
       retries: 3