feat: enhance environment configuration and CORS handling

- Added `NEXT_PUBLIC_APP_URL` and `NEXT_PUBLIC_CONTACT_EMAIL` to environment variables for frontend configuration.
- Updated CORS logic to support domain-based restrictions with dynamic origin validation.
- Improved frontend image hostname resolution using environment-driven URLs.
- Standardized contact email usage across the application.

docker-compose.prod.yml

@@ -131,6 +131,8 @@ services:
     environment:
       NODE_ENV: production
       NEXT_PUBLIC_API_URL: ${NEXT_PUBLIC_API_URL:-https://api.memegoat.fr}
+      NEXT_PUBLIC_APP_URL: ${NEXT_PUBLIC_APP_URL:-https://memegoat.fr}
+      NEXT_PUBLIC_CONTACT_EMAIL: ${MAIL_FROM:-noreply@memegoat.fr}
     depends_on:
       - backend