Data-driven from registry._BUCKET_C (+ cosmos2): each net-new ported arch
resolves through the registry (exact id + arch fallback) AND runs end-to-end on
the CPU toy backend via the public Engine path (resolve -> build card+program ->
load_card -> Engine.run), emitting exactly one modality-correct artifact
(video / image / audio) + latents. Auto-covers future _BUCKET_C rows.
21 tests pass; full v2 mini 232 passed, 2 skipped.