Loras and TI downloads out-of-sync due to multiprocessing

[db0]

Currently Loras and TI MMs in different inference keep their own "knowledge" of ad-hoc downloads, which is probably a problem as they might be deleting each other's files and clobbering the saved file.

• [x] Synchronize read/writes with a multiprocess lock
• [ ] Switch to single process handling of this (a 'download' process or similar) obviating the need to synchronize