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.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' }] },
+};