Add AcceptInviteScreen component to handle user invitation flow with password setup. Add route detection for /accept-invite path in Shell component. Add translation keys for invite acceptance UI in German and English dictionaries (acceptInvite, acceptInviteSubtitle, inviteMissingToken, inviteError, setPassword, saving).
- Change default use_tls from True to False to match typical STARTTLS setup
- Add MailDeliveryError exception for mail delivery failures
- Wrap send_mail calls in try-catch blocks to handle errors gracefully
- Return 502 status code with error details when mail delivery fails
- Add SMTP security mode selector in frontend (STARTTLS/TLS/None)
- Add test mail form to admin panel
- Handle empty SMTP credentials properly in update_mail_settings
- Catch