Restructure into DDD bounded contexts + functional state management

Reorganise from atomic-design-only folders into bounded contexts
(auth / registratie / herregistratie) over a shared kernel, each split into
domain / application / infrastructure / ui layers. Dependencies point inward;
the domain layer is framework-free. Path aliases (@shared/@auth/@registratie/
@herregistratie) make import direction explicit.

State management (Elm-style, native TS, no new deps):
- shared/application/store.ts — createStore(init, update): pure reducer + signal
- shared/application/remote-data.ts — add map/map2/map3/andThen combinators so
  several services fold into one RemoteData; <app-async> gains an [rd] input
- registratie/application/big-profile.store.ts — root singleton combining the
  BIG-register and BRP services via map2 into one state; holds the optimistic
  herregistratie flag shared with the dashboard
- herregistratie: machine gains a WizardMsg union + pure reduce; submit is a
  command that calls infra and dispatches the result, with optimistic update +
  rollback against the shared store
- auth: SessionStore + DigiD adapter + functional route guard; login establishes
  the session, protected routes use canActivate

Rich domain: registration.policy.ts (statusColor/label, herregistratie
eligibility, invariants); BigNummer/Postcode/Uren value objects with smart
constructors. status-badge is now domain-free (colour/label inputs).

Specs for the reducer, RemoteData combinators, and eligibility policy.

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

src/app/shared/layout/site-footer/site-footer.component.ts

@@ -0,0 +1,17 @@
+import { Component } from '@angular/core';
+
+/** Organism: site footer. */
+@Component({
+  selector: 'app-site-footer',
+  styles: [':host{display:block}'],
+  template: `
+    <footer class="utrecht-page-footer" style="background:var(--rhc-color-lintblauw-900,#01689b);color:#fff;margin-top:3rem;width:100%">
+      <div style="max-width:var(--app-content-max);margin:0 auto;padding:1.5rem;display:flex;gap:2rem;flex-wrap:wrap;box-sizing:border-box">
+        <span>BIG-register</span>
+        <span>CIBG — Ministerie van Volksgezondheid, Welzijn en Sport</span>
+        <span style="margin-left:auto;opacity:0.85">Demo / POC — geen echte gegevens</span>
+      </div>
+    </footer>
+  `,
+})
+export class SiteFooterComponent {}