When UpdateService encounters bind address conflicts (port already in use),
the handler now automatically deletes existing forward services and retries
the AddService operation. This resolves issues where a forward's own stale
listener prevents the update.
- Add isBindAddressInUseError() to detect port bind conflicts
- Add rebindForwardServiceOnSelfOccupiedPort() for automatic cleanup and retry
- Add HasOtherForwardOnNodePort() repository method to verify port ownership
- Add unit tests for bind conflict detection