docs: use Tailscale for netdata access instead of basic auth
- Add Tailscale installation to DEPLOY.md server setup
- Update monitoring section to use Tailscale IP:19999
- Remove netdata from Caddyfile (no public exposure)
- Expose netdata port 19999 in docker-compose.prod.yml
- Update architecture diagram to show Tailscale access
๐ค Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>