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/registratie/infrastructure/big-register.adapter.ts

@@ -0,0 +1,20 @@
+import { Injectable } from '@angular/core';
+import { httpResource } from '@angular/common/http';
+import { Registration, Aantekening } from '../domain/registration';
+
+/**
+ * Infrastructure adapter for the BIG-register source. Exposes signal-based
+ * resources (Angular's httpResource); each returns a Resource with
+ * status()/value()/error()/reload(). Call from an injection context
+ * (a field initializer in the store).
+ */
+@Injectable({ providedIn: 'root' })
+export class BigRegisterAdapter {
+  registrationResource() {
+    return httpResource<Registration>(() => 'mock/registration.json');
+  }
+
+  aantekeningenResource() {
+    return httpResource<Aantekening[]>(() => 'mock/notes.json', { defaultValue: [] });
+  }
+}