Small files are committed unchanged (visibility and source.kind stay); large media
are referenced from .stcourses/media.json, ignored, and hard-linked into every
worktree from <dataDir>/media/<id>, where the import folder is moved. Studio writes
to referenced media are refused and never write through a shared inode.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
