Add branching intake wizard (derived steps + radio-group atom)

A second wizard demonstrating a BRANCHING flow: the visible steps are derived
from the answers by a pure `visibleSteps` function rather than stored, so
answering "buiten Nederland gewerkt? -> ja" or reporting few hours adds steps
and the progress denominator changes live. Same Elm-style store + RemoteData
patterns as the fixed wizard; answers persist to localStorage.

- intake.machine.ts: IntakeState union + Answers + visibleSteps + pure reduce (+spec)
- intake-wizard organism, intake.page, submit-intake command
- new radio-group atom (ControlValueAccessor) in shared/ui
- /intake route + dashboard link + concepts showcase section
- tighten Aantekening.type to a 'Specialisme' | 'Aantekening' union
- README + ARCHITECTURE updated

Verified live end-to-end (branches add steps 4->5->6, review, submit) with no
console errors; build, unit tests, and Storybook all green.

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

src/app/shared/ui/radio-group/radio-group.component.ts

@@ -0,0 +1,50 @@
+import { Component, forwardRef, input } from '@angular/core';
+import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';
+
+export interface RadioOption {
+  value: string;
+  label: string;
+}
+
+/** Atom: a radio group. Thin wrapper over the Utrecht/RHC radio CSS, wired as a
+    form control so it works with ngModel just like the text-input atom. */
+@Component({
+  selector: 'app-radio-group',
+  template: `
+    <div class="utrecht-form-field-radio-group" role="radiogroup">
+      @for (opt of options(); track opt.value) {
+        <label class="utrecht-form-label utrecht-form-label--radio-button" style="display:flex;align-items:center;gap:0.5rem;padding:0.25rem 0">
+          <input
+            class="utrecht-radio-button"
+            type="radio"
+            [name]="name()"
+            [value]="opt.value"
+            [checked]="value === opt.value"
+            [disabled]="disabled"
+            (change)="select(opt.value)"
+            (blur)="onTouched()" />
+          {{ opt.label }}
+        </label>
+      }
+    </div>
+  `,
+  providers: [{ provide: NG_VALUE_ACCESSOR, useExisting: forwardRef(() => RadioGroupComponent), multi: true }],
+})
+export class RadioGroupComponent implements ControlValueAccessor {
+  options = input.required<RadioOption[]>();
+  name = input.required<string>();
+
+  value = '';
+  disabled = false;
+  onChange: (v: string) => void = () => {};
+  onTouched: () => void = () => {};
+
+  select(v: string) {
+    this.value = v;
+    this.onChange(v);
+  }
+  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; }
+}

src/app/shared/ui/radio-group/radio-group.stories.ts

@@ -0,0 +1,17 @@
+import type { Meta, StoryObj } from '@storybook/angular';
+import { RadioGroupComponent } from './radio-group.component';
+
+const meta: Meta<RadioGroupComponent> = {
+  title: 'Atoms/RadioGroup',
+  component: RadioGroupComponent,
+  render: (args) => ({
+    props: args,
+    template: `<app-radio-group [options]="options" [name]="name" />`,
+  }),
+};
+export default meta;
+type Story = StoryObj<RadioGroupComponent>;
+
+export const JaNee: Story = {
+  args: { name: 'voorbeeld', options: [{ value: 'ja', label: 'Ja' }, { value: 'nee', label: 'Nee' }] },
+};