[Bug] Multiple repair crews can spawn and move into the same square

Steps to reproduce

Launch Basic and join the player ship's Engineering screen. Repeat until two or more repair crews are randomly spawned into the same interior cell.

Or:

1. Launch Basic and join the player ship's Engineering screen.
2. Select a repair crew.
3. Click/tap a cell far from its current location to move the selected crew into that cell.
4. Quickly select another repair crew, then click/tap to move it into the same cell as the previous crew.

Expected behavior

Multiple repair crews can't overload a single interior cell.

Observed behavior

Multiple crew can fit into the same interior cell. For example, on an Atlantis it's possible to fit all three crew into a single cell. This allows repairing a two-cell room with three repair crew.

https://github.com/user-attachments/assets/fbcd4de7-fb6d-4088-9bd5-cc6a2ad8f863

If this behavior is expected, then the bug is that repair crew selection prevents moving additional crew into an already occupied cell.

Start at the player ship's Engineering screen and reproduce both the random-spawn and rapid-movement cases described. Trace repair crew selection and movement from that entry point, then verify that an interior cell cannot contain multiple repair crews, or confirm the intended selection behavior if occupied-cell movement is allowed.