Module command_queue 

Per-frame context + legacy name: used to be a command queue.

This is a transitional facade that stages signals locally and drains them into RxWorld at explicit drain points.

Important safety note:

• This type must not store raw pointers into SystemWorld/RxWorld owned alongside it (e.g. in Universe), because moving that owner would invalidate the pointer.
• Instead, we queue signals locally and drain them into SystemWorld.rx at explicit drain points.

Structs

CommandQueue