Move Ava-specific worker infrastructure from Omni/Agent/Subagent/ to Omni/Ava/.
Files to move:
- Omni/Agent/Subagent/Worker.hs -> Omni/Ava/Worker.hs
- Omni/Agent/Subagent/Jobs.hs -> Omni/Ava/Jobs.hs
Update:
- Module names
- All imports referencing these files
- The ava-worker binary output name if needed