feat: scroll-driven maintenance window set-piece in the infrastructure chapter

tests/unit/AppShell.test.ts

@@ -150,3 +150,15 @@ describe('semantic portfolio document', () => {
     expect(document.body.textContent).toContain('Footy Tracker');
   });
 });
+
+describe('the 03:12 window on the server', () => {
+  it('ships no maintenance step and an empty, hidden HUD sub-line', async () => {
+    const html = await render('/', validInputs);
+    expect(html).not.toContain('data-maintenance-step');
+    expect(html).not.toContain('MAINTENANCE WINDOW');
+    const document = await renderedDocument();
+    const subline = document.querySelector('.journey-hud__subline');
+    expect(subline).not.toBeNull();
+    expect(subline?.textContent).toBe('');
+  });
+});