- Use getMimeType() instead of getClientMimeType() to prevent MIME spoofing
- Change IsGranted to IS_AUTHENTICATED_FULLY so ROLE_CLIENT can access avatars
- Remove Groups from avatarFileName (only avatarUrl needed by frontend)
- Disable aggressive caching to prevent stale avatar images
- Add error handling to avatar upload in profile page
- Use i18n for "Mon profil" button text
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>