Create:CompactMachinesPOR

This release fixes a production server hang (ServerHangWatchdog timeout) caused by evaluation code performing full-dimension synchronous saves and unbounded I/O waits inside the server tick.

What changed

Evaluation start / source-room freezing no longer calls ServerLevel.save(true) on the whole dimension or waits for the global I/O worker. The source room is now left to the vanilla chunk-unload pipeline, which submits each chunk to its own I/O worker; evaluation only proceeds once all room chunks and entities are truly idle. Rollback no longer saves the entire machine dimension. After restoring the original machine, only the machine's single chunk is serialized and written asynchronously; the session is only closed after that write completes. Replica publishing/cleanup now writes entity and POI data asynchronously via futures; blocking flushAll() / synchronize(true).join() calls were removed from server-tick paths. The critical journal remains the crash-recovery anchor for Phase 4 cleanup responsibility.