The dedicated server was spawning a host avatar (peer 1) via
player-spawner._handle_host() and _handle_new_peer(1) on startup,
which registered RollbackSynchronizer subjects with the netfox
rollback system. Since no client input exists for peer 1, the
rollback system tried to record state for freed/recycled objects,
flooding the log with property-pool.gd errors.
Fix:
- Add spawn_host_avatar @export flag to player-spawner.gd
- Set it false in headless_server.gd before starting the ENet server
- PlayerSpawner._handle_host() skips avatar spawn when flag is false
- PlayerSpawner._handle_new_peer(1) skips avatar spawn when flag is false
Server startup is now clean: no property-pool errors, no RPC path errors.
