Cards become JSON data in course/cards (one file per card, validated
against card.schema.json and the catalog); the M5 references load them
via registerCards and interpret effects, replacing content closures.
Adds assemble(base, donor, half), the assemble/buffHand effects with an
injected chooser, Fleshshape as the data-only Expansion Drop, and stages
course/cards in verify-references and start-module.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
