add-torch-shapes-example

You are importing a PyTorch model into Pyrefly's example corpus at tensor-shapes/pyrefly-torch-stubs/examples/. This is the contribution case the porting skill describes: these ports are tested reference material that others read to learn the patterns, so produce its fuller deliverable — paste every artifact (audit table, per-local reveal_type dumps, typed-interface receipts, exhaustive assert_type coverage, completion report) in full, not just the annotated model.

Why these ports matter. They demonstrate what happens when you write a real PyTorch model with tensor shape types, proving real-world utility. If you exclude features or simplify the model, you prove nothing — the hard parts are exactly where the value needs to be demonstrated. So port the model faithfully and in full (see step 2).