Walkthrough of the three W1 commits, the 4090 result (50 steps in ~1s,
loss 5.55 → 0.17), and the limitations to keep in mind before reading
into the loss-down (LM is also random + tiny vocab, so the drop is
mostly memorisation, not Whisper-Projector alignment — W2 freezes the
LM specifically to test that). Includes the W2 hand-off checklist.
Fam Zheng