build-data

Create the feature's `data/` layer (pure spec; depends on nothing but `@adobe/data` and other `data/` declarations): - one namespace folder per data type — `<type>/{<type>.ts, schema.ts, public.ts, <helper>.ts}`; - `data/state/` — the `State` aggregate plus its pure transforms/derivations. The schema is the single source of truth; the type derives from it (`Schema.ToType`). Helpers are pure and unit-tested. Run this first — every other layer imports `data/`. The how is in the auto-loading rules: `features/data/index.md`, `data/state.md`, and `namespace.md`.