Problem:
use_new_version returned 404 annotation not found for files without
annotation, preventing users from switching to new versions.
Solution:
1. Query latest file by logical_path
2. Update LabelingProjectFile to point to latest version
3. If annotation exists: clear it and update file_id
4. If no annotation: just update project file snapshot
5. Return new file_id in response
q792602257
cd5f5ef6da