test(trip): specs for trip one-liner, description, banner & home gating

- trips-list.spec.js: one-liner presence/absence, retina srcset, cover
  fallback, alt text (U3).
- trip-header.spec.js: HTD stacking order, expandable description, banner
  fallback, split intact (U4).
- home.spec.js: AE7 — the gated trip-page extras never leak onto the home
  route (asserted mode-independently so it can't race the home-highlights
  suite that toggles travelling in a parallel worker).

Also marks the plan complete.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RDS6t8wcpbwKvvrxykVQ5K

tests/ui/home/home.spec.js

@@ -1,5 +1,5 @@
 // @ts-check
-// Tests: H1 — home page journal feed
+// Tests: H1 — home page journal feed; AE7 — active-trip header gating
 const { test, expect } = require('@playwright/test');
 
 // ── H1: Home page renders inline journal posts ─────────────────────────────────
@@ -8,3 +8,17 @@ test('H1: home page shows at least one inline journal-post block', async ({ page
     await expect(page.locator('.journal-post').first()).toBeVisible();
     await expect(page.locator('.site-header')).toBeVisible();
 });
+
+// ── AE7: the trip-page header extras never leak onto the home route ────────────
+// The trip-page one-liner/description/banner are gated to the trip.html.twig
+// caller of the shared trip-feed-col partial (trip_header_extras, default off);
+// home's include omits the flag, so its header is unchanged (R12/KTD4). Asserted
+// as an absence on `/` so it holds whether home is in active-trip or
+// between-trips mode — the sibling home-highlights suite toggles that mode in a
+// parallel worker, so this test must not depend on it.
+test('AE7: home never renders the trip-page header extras', async ({ page }) => {
+    await page.goto('/');
+    await expect(page.locator('.home-trip-tagline')).toHaveCount(0);
+    await expect(page.locator('.trip-header-desc')).toHaveCount(0);
+    await expect(page.locator('.trip-header-banner')).toHaveCount(0);
+});