docs: index orphaned reference docs + add scaffolding guide

- Index roles-and-access, dependencies, and dependency-graph (were on disk
  but missing from the docs README index).
- New reference/scaffolding.md: plop generators, gen:api (NSwag), gen:snippets,
  and the skill recipes — the one consolidated "how generation works" page.
- Fix stale backlog range (WP-01…WP-28 -> WP-48) and de-link the dead WP-32 row
  (undo folded into WP-31, no separate file).

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

docs/project/backlog/README.md

@@ -76,7 +76,7 @@ for its existing violations, so every WP ends green.
 | [WP-29](WP-29-stamdata-beheer-editor.md)       | Stamdata beheer editor (low-code, PR-emitting)                                     | follow-on · ADR-0004        | done   |
 | [WP-30](WP-30-ci-perf-followups.md)            | CI performance follow-ups (node_modules cache, runner image, path filters)         | follow-on · CI/infra        | todo   |
 | [WP-31](WP-31-shared-store-helpers.md)         | Shared store helpers (ActionState/SaveState, history, debounced-save, RemoteData)  | 7 · refinements             | done   |
-| [WP-32](WP-32-stamdata-undo.md)                | Undo/redo in the stamdata editor                                                   | 7 · refinements             | done   |
+| WP-32                                          | Undo/redo in the stamdata editor (folded into WP-31 — no separate file)            | 7 · refinements             | done   |
 | [WP-33](WP-33-dev-switchers.md)                | In-app dev switchers (scenario + role)                                             | 7 · refinements             | done   |
 | [WP-34](WP-34-adres-phone-brp-readonly.md)     | Adres: phone field + BRP address read-only                                         | 7 · refinements             | done   |
 | [WP-35](WP-35-one-concept-per-type.md)         | One Concept per case type (server-enforced)                                        | 7 · refinements             | done   |