feat(bootstrap): fall back to built-in placeholder when marketplace unpublished

Adds published: boolean to the bootstrap wire contract. ConfigService
swaps to a new DEFAULT_BOOTSTRAP constant (all feature flags on, generic
branding/theme/pages) whenever the backend reports published: false, so
an unpublished marketplace renders a working demo instead of a blank or
broken page. Missing published field stays backward compatible (treated
as true). Documents the brand bootstrap wire shape for backend/ops use.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

e2e/smoke.spec.ts

@@ -32,4 +32,22 @@ test.describe('smoke', () => {
 
     expect(errors, `console errors on first paint: ${errors.join('\n')}`).toEqual([]);
   });
+
+  test('renders the placeholder home page when the marketplace is unpublished', async ({ page }) => {
+    // This suite runs against the mock-data build (see comment at the top of
+    // playwright.config.ts), so MockBootstrapProvider fetches this static
+    // asset rather than a live /bootstrap endpoint - that's the URL to
+    // intercept here, not the real API path.
+    await page.route('**/assets/mock/bootstrap/bootstrap.json', route =>
+      route.fulfill({
+        status: 200,
+        contentType: 'application/json',
+        body: JSON.stringify({ schemaVersion: '1.0.0', generatedAt: new Date().toISOString(), published: false }),
+      })
+    );
+
+    await page.goto('/');
+
+    await expect(page.getByText('Welcome to Marketplace')).toBeVisible();
+  });
 });