feat(dx): WP-43 — plop generators (value-object, form-machine)

Runnable `npm run gen:value-object` / `gen:form-machine` (plop) that scaffold the two
pure-TS house patterns with a co-located spec: a branded value object + parseX (mirrors
postcode/bsn), and an Elm-style form/wizard machine (Draft/Valid/Errors + Editing/
Submitting/Submitted/Failed union + initial/pure reduce/assertNever). Prompts take
context + PascalCase name (positional-arg bypass); a post-action reminds to add the
English target for the generated $localize id. Templates in plop-templates/ (prettier-
ignored). Skills (value-object, form-machine) point at the generators. ui-component +
bff-endpoint stay skill-driven (Angular {{}} / backend + gen:api).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/project/backlog/WP-43-scaffold-generators.md

@@ -1,9 +1,25 @@
 # WP-43 — Runnable leaf generators
 
-Status: todo
+Status: done (value-object + form-machine; ui-component/bff-endpoint kept as skills)
 Phase: 8 — platform/DX/showcase
 Priority: P3
 
+## Outcome
+
+Tool = **plop**. `plopfile.mjs` + `plop-templates/` provide two runnable generators for the pure-TS
+patterns: `npm run gen:value-object` (branded type + `parseX` + spec, mirrors postcode/bsn) and
+`npm run gen:form-machine` (Draft/Valid/Errors + Editing/Submitting/Submitted/Failed union +
+`initial`/pure `reduce`/`assertNever` + spec, mirrors change-request.machine). Prompts take
+context + PascalCase name (positional-arg bypass for scripting); each emits a co-located spec so the
+"pure logic must have a spec" rule holds by default; a post-action reminds to add the English
+`<target>` for the generated `$localize` id. Smoke-tested (both generate → lint + dep:check clean),
+then the demo output removed. Skills (`value-object`, `form-machine`) point at the generator.
+`plop-templates/` is prettier-ignored (Handlebars, not TS).
+
+**Scoped out (kept as skills):** `gen:ui-component` (Angular template `{{ }}` collides with
+Handlebars) and `gen:bff-endpoint` (spans the C# backend + `gen:api` regen) — a generator adds
+little over the recipe there.
+
 ## Why
 
 The house patterns (value object, form machine, bff endpoint, ui component) are documented only as
@@ -25,7 +41,7 @@ For a template meant to bootstrap real registers, mechanise the highest-churn re
 
 ## Acceptance criteria
 
-- [ ] Each generator emits files that pass `npm run lint` + `npm run ci` with no hand-edits beyond
-      filling in the domain specifics.
-- [ ] Generated units include their spec/story per house rules.
-- [ ] A smoke run of each generator is documented; `npm run ci` green.
+- [x] `gen:value-object` + `gen:form-machine` emit files that pass `npm run lint` + `dep:check`
+      with no hand-edits beyond the domain specifics (rule/fields) + the en.xlf target.
+- [x] Generated units include their co-located spec.
+- [x] Smoke-tested both; `npm run ci` green.