feat(trips): owner publish/unpublish toggle on /trips listing

Add an owner-only publish switch to each /trips card. It POSTs to a new
entry-actions route that mutates trip.md `published` and invalidates the
page-tree cache so the listing, nav and home reflect the change on the
next load. Owner sees drafts (Draft badge); anon/non-owner unchanged.

- U1 EntryScopeGuard::resolveTripChild — resolve a slug to a direct child
  of /trips (drafts included, for republish)
- U2 POST /api/v1/trip/{slug}/publish (setTripPublished) — owner-gated
  write, strict is_bool body, header-mutation save, audit log
- U3 trip-publish-toggle partial + CSS (role=switch, Draft badge, visible
  failure toast, ≥44px target)
- U4 owner-aware /trips listing + card restructure (toggle overlays cover
  as a non-anchor sibling; works for coverless drafts)
- U5 home active-trip branch falls back when the active trip is unpublished
- U6 trip-publish.js (confirm/pending/optimistic/revert) + esbuild wiring

Cache note: an in-place frontmatter edit keeps the folder-check cache id,
and driver:auto uses APCu in web memory, so deleteAll()+invalidateCache()
is insufficient — the endpoint also calls apcu_clear_cache().

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Mpdu3Dt1iVoozHwAMyjrbn

themes/intotheeast/templates/home.html.twig

@@ -9,7 +9,10 @@
 {% set trip_route = config.site.active_trip %}
 {% set trip = grav.pages.find(trip_route) %}
 
-{% if config.site.travelling %}
+{# An unpublished active trip falls through to the between-trips state (R16,
+   KTD7): trip is resolved above and `.published` reads the trip.md flag. This is
+   the whole home fallback — site.active_trip is not touched. #}
+{% if config.site.travelling and trip and trip.published %}
 {# ══════════════════════════════════════════════════════════ ACTIVE TRIP MODE #}
 
 {% set dailies_page = grav.pages.find(trip_route ~ '/dailies') %}