feat: add per-trip use_gpx and autoconnect toggles

Adds two configurable toggles to the trip blueprint (Admin2 Trip tab):
- use_gpx: show/hide GPX tracks on all maps (default: enabled)
- autoconnect: draw connector lines between markers (default: enabled)

When use_gpx is off, GPX files are not fetched or rendered on any map
(home, map, trip, dailies). The stats panel in trip.html.twig still
reads GPX_URLS directly and is unaffected.

When autoconnect is off, buildJourneySegments suppresses all
auto-connectors; only entries with force_connect:true still draw a
line — making force_connect behaviour independent of both settings.

Also refactors the inline Promise.all in trip.html.twig to use the
shared renderGpxJourney utility (reducing duplication).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vgmzx8VTTTmCskSpQtsLTr

themes/intotheeast/blueprints/trip.yaml

@@ -55,6 +55,30 @@ form:
               placeholder: '6 weeks from Venice to Sicily by train'
               help: 'Short description shown on homepage highlight cards'
 
+            header.use_gpx:
+              type: toggle
+              label: Show GPX tracks
+              help: 'Display GPX route files on the map'
+              highlight: 1
+              default: 1
+              options:
+                1: 'Yes'
+                0: 'No'
+              validate:
+                type: bool
+
+            header.autoconnect:
+              type: toggle
+              label: Connect markers
+              help: 'Draw connector lines between location markers (suppressed where GPX covers the route)'
+              highlight: 1
+              default: 1
+              options:
+                1: 'Yes'
+                0: 'No'
+              validate:
+                type: bool
+
         publishing:
           type: tab
           title: Publishing