test(fixture): add no-photos-demo trip for AE4 coverage

A minimal demo trip with no cover_image and a single published journal entry
that has no images — the fixture the trip-page banner AE4 assertion needs
(macro fallback loop finds an entry but no image -> null cover -> no banner
strip). Lives under docs/demo/trips/ like italy-2026-demo, so it is loaded into
the pages tree only for tests and never reaches live content.

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

docs/demo/trips/no-photos-demo/dailies/2027-01-10-1000-first-light.entry/entry.md

@@ -0,0 +1,18 @@
+---
+title: 'First Light on the Road'
+date: '2027-01-10 10:00'
+template: entry
+published: true
+hero_image: ''
+lat: 60.17
+lng: 24.94
+location_city: Helsinki
+location_country: Finland
+weather_temp_c: -6
+weather_desc: Clear
+---
+
+The bus left before dawn and the city was still under snow. I wrote most of
+this by the window with a cold coffee, watching the harbour lights slide past.
+No photographs today — the light was flat and grey and would not have kept
+anyway. Some mornings the notebook is the only camera worth carrying.