Chore: Bump Docker demo environment PHP file upload size limit to 8MB

Summary

In the local Docker demo environment, media uploads (images, WXR import files, themes...) larger than PHP's 2MB default were failing. Bumping upload_max_filesize and post_max_size to 8MB permits testing realistic media assets without modifying memory limits.

Proposed Solution

1. Add docker-demo/uploads.ini configuring PHP upload directives:
   • upload_max_filesize = 8M
   • post_max_size = 8M
2. Mount uploads.ini into both the wp (Apache/PHP) and init (CLI) container services in docker-compose.yml

Acceptance Criteria

• Docker demo permits file uploads up to the configured limit without PHP upload errors.

Commencez par docker-compose.yml et inspectez les services wp et init existants, puis examinez la configuration proposée de docker-demo/uploads.ini. Montez le fichier dans les deux services avec les deux directives PHP spécifiées et vérifiez que la démo Docker autorise les téléversements jusqu’à 8MB sans erreurs de téléversement PHP.