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/ui/change-request-form/change-request-form.component.ts

@@ -0,0 +1,59 @@
+import { Component, output, signal } from '@angular/core';
+import { FormsModule } from '@angular/forms';
+import { FormFieldComponent } from '@shared/ui/form-field/form-field.component';
+import { TextInputComponent } from '@shared/ui/text-input/text-input.component';
+import { ButtonComponent } from '@shared/ui/button/button.component';
+import { HeadingComponent } from '@shared/ui/heading/heading.component';
+import { Postcode, parsePostcode } from '@registratie/domain/value-objects/postcode';
+
+/** A submitted change request carries a *parsed* postcode (branded Postcode),
+    not a raw string — downstream code can't receive an unvalidated one. */
+export interface ChangeRequest {
+  street: string;
+  zip: Postcode;
+  city: string;
+}
+
+/** Organism: change-request (adreswijziging) form. Reuses the same form-field
+    molecule + text-input/button atoms as the login form. Field errors come
+    straight from the parser's Result — no parallel "is it valid" flag to drift. */
+@Component({
+  selector: 'app-change-request-form',
+  imports: [FormsModule, FormFieldComponent, TextInputComponent, ButtonComponent, HeadingComponent],
+  template: `
+    <app-heading [level]="2">Adreswijziging doorgeven</app-heading>
+    <form (ngSubmit)="onSubmit()" style="max-width:28rem">
+      <app-form-field label="Straat en huisnummer" fieldId="street" [error]="streetError()">
+        <app-text-input inputId="street" [(ngModel)]="street" name="street" [invalid]="!!streetError()" />
+      </app-form-field>
+      <app-form-field label="Postcode" fieldId="zip" [error]="zipError()">
+        <app-text-input inputId="zip" [(ngModel)]="zip" name="zip" placeholder="1234 AB" [invalid]="!!zipError()" />
+      </app-form-field>
+      <app-form-field label="Woonplaats" fieldId="city">
+        <app-text-input inputId="city" [(ngModel)]="city" name="city" />
+      </app-form-field>
+      <div style="margin-top:1rem">
+        <app-button type="submit" variant="primary">Wijziging indienen</app-button>
+      </div>
+    </form>
+  `,
+})
+export class ChangeRequestFormComponent {
+  street = '';
+  zip = '';
+  city = '';
+  streetError = signal('');
+  zipError = signal('');
+  submitted = output<ChangeRequest>();
+
+  onSubmit() {
+    const street = this.street.trim();
+    this.streetError.set(street ? '' : 'Vul straat en huisnummer in.');
+
+    const postcode = parsePostcode(this.zip);
+    this.zipError.set(postcode.ok ? '' : postcode.error);
+
+    if (!street || !postcode.ok) return;
+    this.submitted.emit({ street, zip: postcode.value, city: this.city.trim() });
+  }
+}