- Add public page at /email/change-password for Poste.io mailbox password management
- Add API routes for SMTP credential verification and Poste.io password change
- Rewrite nginx config as HTTP-only (certbot --nginx will add SSL)
- Add Poste.io admin API env vars to docker-compose and env templates
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>