Track *.epub, *.pdf, *.mp3/wav/m4a/mp4/mov/webm, *.wasm via Git LFS so
future additions stop compounding the clone-size problem. Existing
history is NOT migrated by this change — see issues #1393 and #1175 for
the planned Phase 2 (`git lfs migrate import`, force-push, team re-clone)
which requires VJ approval and coordinated rollout.
Mixed-size patterns (*.png, *.jpg, *.gif) are deliberately omitted: the
repo has thousands of small icon PNGs alongside 1-5 MB cover art / kit
photos and a blanket pattern would LFS-track the small ones too. Leaving
those for VJ to scope by path.
Relates to #1393, #1175.
