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/ui/skeleton/skeleton.component.ts

@@ -0,0 +1,33 @@
+import { Component, OnDestroy, OnInit, computed, input, signal } from '@angular/core';
+
+/** Atom: skeleton placeholder (grey shimmer). Delay-gated so it never flashes
+    on fast responses. Render `count` lines shaped roughly like the content. */
+@Component({
+  selector: 'app-skeleton',
+  styles: [`
+    :host{display:block}
+    .sk{background:linear-gradient(90deg,#e8ebee 25%,#f3f5f6 37%,#e8ebee 63%);
+        background-size:400% 100%;animation:sh 1.4s ease infinite;border-radius:4px;
+        margin-block-end:0.6rem}
+    @keyframes sh{0%{background-position:100% 0}100%{background-position:0 0}}
+  `],
+  template: `
+    @if (visible()) {
+      @for (l of lines(); track $index) {
+        <div class="sk" [style.width]="width()" [style.height]="height()"></div>
+      }
+    }
+  `,
+})
+export class SkeletonComponent implements OnInit, OnDestroy {
+  width = input('100%');
+  height = input('1rem');
+  count = input(1);
+  delay = input(150);
+  protected visible = signal(false);
+  protected lines = computed(() => Array(this.count()).fill(0));
+  private timer?: ReturnType<typeof setTimeout>;
+
+  ngOnInit() { this.timer = setTimeout(() => this.visible.set(true), this.delay()); }
+  ngOnDestroy() { clearTimeout(this.timer); }
+}

src/app/shared/ui/skeleton/skeleton.stories.ts

@@ -0,0 +1,13 @@
+import type { Meta, StoryObj } from '@storybook/angular';
+import { SkeletonComponent } from './skeleton.component';
+
+const meta: Meta<SkeletonComponent> = {
+  title: 'Atoms/Skeleton',
+  component: SkeletonComponent,
+  args: { delay: 0 },
+};
+export default meta;
+type Story = StoryObj<SkeletonComponent>;
+
+export const SingleLine: Story = { args: { width: '60%', height: '1rem' } };
+export const CardPlaceholder: Story = { args: { height: '2.5rem', count: 6 } };