Write the eight domain-model cards under `docs/models/`, mark M10 10i
Done, and update the design docs to v16. Also records Doc 44, which
ratifies Decisions 129-133 as amended, and the Doc-39 conformance
check that satisfied its gate.
Introduce `docs/models/` with the catalog index and its first card
(product-catalog), recording invariants, dimensions, and drift traps
per the Decision 141 documentation division. Add the model-cards
openspec change (proposal, design, spec, tasks) and sync the design
docs to v15: product kind taxonomy dissolved (Decisions 134–139),
Decisions 140–141 ratified, and product/pricing helpers updated. The
catalog is the single descriptive home for as-built models.
cgalo5758