refactor(workshop): domain is name-only; Module 1 carries it read-only

Phase 2 "Pick your domain": drop the Refine button + the four-dimension
generation machinery — just capture the domain name and save it for the
modules ahead (DomainPicker is now a single input).

Module 1: show the domain the team named on the previous screen as
read-only ("Your domain" carried over), and remove the "Open your node"
inline link + the editable domain field.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/pages/Module1.test.tsx

@@ -38,6 +38,15 @@ describe('Module1', () => {
     ).toHaveAttribute('data-state', 'active')
   })
 
+  it('shows the domain carried over from the earlier screen (read-only)', () => {
+    useSession.getState().setDomain('air quality')
+    renderPage()
+    const carried = screen.getByTestId('domain-carried')
+    expect(carried).toHaveTextContent('air quality')
+    // no editable domain input here anymore
+    expect(screen.queryByLabelText(/your domain/i)).toBeNull()
+  })
+
   it('renders the actor map and the live board feed', () => {
     renderPage()
     expect(screen.getByTestId('actor-map')).toBeInTheDocument()