feat(fp): WP-14 — Storybook taxonomy reorg + Layers MDX

Retitle all 49 stories into a sidebar that makes the DDD seam visible:
Foundations (curriculum) -> Design System (Atoms/Molecules/Organisms/
Templates/Devtools, everything in shared/ui + shared/layout) -> Domein
(Registratie/Herregistratie/Auth/Brief, everything in a context's ui/).
Pin the order via storySort. Add layers.mdx explaining the split and
linking the enforcing eslint rules; document the story-title convention
in CLAUDE.md. Fix a stale "status banner" reference in atomic-design.mdx
left over from WP-13's upload-status-banner deletion.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/herregistratie/ui/herregistratie-wizard/herregistratie-wizard.stories.ts

@@ -10,7 +10,7 @@ import { Uren } from '@registratie/domain/value-objects/uren';
 const validData = { uren: 4160 as Uren, jaren: 5, punten: 200, documents: [] };
 
 const meta: Meta<HerregistratieWizardComponent> = {
-  title: 'Herregistratie/Wizard',
+  title: 'Domein/Herregistratie/Wizard',
   component: HerregistratieWizardComponent,
   // The wizard injects BigProfileStore (for the optimistic cross-page flag),
   // which creates httpResources — so the story needs an HttpClient.

src/app/herregistratie/ui/intake-wizard/intake-wizard.stories.ts

@@ -9,7 +9,7 @@ import { Uren } from '@registratie/domain/value-objects/uren';
 const validData = { werktBuitenland: false, uren: 4160 as Uren, punten: 200 as Uren };
 
 const meta: Meta<IntakeWizardComponent> = {
-  title: 'Herregistratie/IntakeWizard',
+  title: 'Domein/Herregistratie/IntakeWizard',
   component: IntakeWizardComponent,
   // Injects BigProfileStore (optimistic flag) which creates httpResources.
   decorators: [applicationConfig({ providers: [provideHttpClient(), provideApiClient()] })],