Fix story scrolly text rendering; story/trip blueprint media upload

Scrolly-section text never rendered: the inline Scrollama block ran before
the main.js bundle published window.scrollama, so it always hit its guard
and the panel text stayed display:none, leaving a blank column beside the
pinned image. Defer to DOMContentLoaded, and build the step panels before
the scrollama check so a missing bundle costs the animation, not the text.

Also fixes an invalid calc(-(...)) that dropped the mobile scrolly offset,
and drops the duplicate inline back-to-top in favour of main.js's version
(which pushes a history entry).

Blueprint changes carried over from an earlier session: story.yaml and
trip.yaml now extend the default page form so both can upload media.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

themes/intotheeast/blueprints/trip.yaml

@@ -1,5 +1,13 @@
 title: 'Trip'
 
+# Inherits Grav's default page form — this is what supplies the page-media
+# uploader (used for cover images and GPX files), plus the standard Options and
+# Advanced tabs. Without it the form is standalone and can only *select*
+# existing media, never upload any.
+'@extends':
+    type: default
+    context: blueprints://pages
+
 form:
   fields:
     tabs:
@@ -8,6 +16,7 @@ form:
       fields:
 
         content:
+          ordering@: 0
           type: tab
           title: Content
           fields:
@@ -21,7 +30,15 @@ form:
               type: markdown
               label: Description
 
+            # Inherited from the default blueprint; relabelled because this is
+            # also where GPX files and cover images get uploaded.
+            header.media_order:
+              type: pagemedia
+              label: Images and GPX files
+              help: 'Upload cover images and .gpx route files here. GPX tracks are auto-detected on the map — no manual linking. The Cover Image field below picks from what is uploaded here.'
+
         trip:
+          ordering@: 1
           type: tab
           title: Trip
           fields:
@@ -78,17 +95,6 @@ form:
                 'manual': 'Manual — force connect only'
                 'intelligent_gpx': 'Intelligent GPX — suppress where route is covered'
 
-        publishing:
-          type: tab
-          title: Publishing
-          fields:
-            header.published:
-              type: toggle
-              label: Published
-              highlight: 1
-              default: 1
-              options:
-                1: 'Yes'
-                0: 'No'
-              validate:
-                type: bool
+        # No Publishing tab — it held only the Published toggle, which now comes
+        # from the inherited Options tab. Defining it here too would render two
+        # toggles bound to the same header key.