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/text-input/text-input.component.ts

@@ -0,0 +1,40 @@
+import { Component, forwardRef, input } from '@angular/core';
+import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';
+
+/** Atom: text input. Utrecht textbox wired up as a form control (ngModel/reactive). */
+@Component({
+  selector: 'app-text-input',
+  template: `
+    <input
+      class="utrecht-textbox rhc-text-input"
+      [class.utrecht-textbox--invalid]="invalid()"
+      [type]="type()"
+      [id]="inputId()"
+      [placeholder]="placeholder()"
+      [disabled]="disabled"
+      [value]="value"
+      (input)="onInput($event)"
+      (blur)="onTouched()" />
+  `,
+  providers: [{ provide: NG_VALUE_ACCESSOR, useExisting: forwardRef(() => TextInputComponent), multi: true }],
+})
+export class TextInputComponent implements ControlValueAccessor {
+  type = input<'text' | 'password' | 'email'>('text');
+  placeholder = input('');
+  invalid = input(false);
+  inputId = input<string>();
+
+  value = '';
+  disabled = false;
+  onChange: (v: string) => void = () => {};
+  onTouched: () => void = () => {};
+
+  onInput(e: Event) {
+    this.value = (e.target as HTMLInputElement).value;
+    this.onChange(this.value);
+  }
+  writeValue(v: string) { this.value = v ?? ''; }
+  registerOnChange(fn: (v: string) => void) { this.onChange = fn; }
+  registerOnTouched(fn: () => void) { this.onTouched = fn; }
+  setDisabledState(d: boolean) { this.disabled = d; }
+}