[Bug] last_modified not updating after transforms #244
Description
Describe the bug
The Project model has a last_modified column used to order the homescreen 'Recently Modified' list. Before this fix, last_modified was only stamped at project creation — it was never updated when a transformation was applied. This meant the homescreen always ordered projects by upload time, not by actual activity. Projects you were actively working on would sink below projects that were uploaded more recently but untouched.
Expected behavior
Whenever an existing file is modifed then the recent file order should be updated accordingly