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>