docs: add Cloudflare tunnel migration notes ...

- cloudflared moved from Docker on .243 to systemd on .244
- tunnel ha.sky-it.pl -> 192.168.50.151:8123
- 4 active connections to Cloudflare edge

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

docs: add OpenVPN migration notes to Proxmox LXC doc ...

- Hostname changed to s2GLU7xMReVscAtcdTqZ25
- Both OpenVPN connections running on .244
- Documented OpenSSL 3.5/SHA1 workaround, TUN fix, Type=forking fix
- Old .243 OpenVPN disabled

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

feat: IBSystem MQTT bridge migrated to Proxmox LXC 103 (192.168.50.244) ...

- Added systemd service files: ibvunit.service, ibsystem2mqtt.service
- ibvunit connects to RS485 converter at 192.168.50.50:20108
- ibsystem2mqtt depends on ibvunit (Requires=)
- Both services auto-start enabled on new LXC
- Watchdog cron installed: /ibsystem/watchdog.sh
- Old .243 services disabled (HA Docker stays on .243)
- Status: 17 devices, 356 entities, MQTT online, 0 errors

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>