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>

package.json

@@ -20,6 +20,9 @@
     "dep:check": "depcruise src/app --config .dependency-cruiser.js",
     "dep:graph": "bash scripts/dep-graph.sh",
     "gen:snippets": "node scripts/gen-snippets.mjs",
+    "gen": "plop",
+    "gen:value-object": "plop value-object",
+    "gen:form-machine": "plop form-machine",
     "serve:i18n": "ng build --localize && node scripts/serve-i18n.mjs",
     "ci": "bash scripts/ci-local.sh",
     "e2e": "playwright test",
@@ -62,6 +65,7 @@
     "http-server": "^14.1.1",
     "jsdom": "^29.0.0",
     "nswag": "^14.7.1",
+    "plop": "^4.0.5",
     "prettier": "^3.8.1",
     "remark-gfm": "^4.0.1",
     "storybook": "^10.4.6",