1086436 creates Viewer.js only once the image has loaded, so the
"Viewer.js could not load" reason moved from the instance to the live
window.Viewer. An image shown natively while Viewer.js was missing then
offered transforms as soon as Viewer.js reappeared, which
full-inspector.spec.mjs:854 ("collection viewer preserves original
download and rooted retries") caught on every project.
Each rebuild now captures the Viewer.js it builds with. The reason, the
native fallback and the later construction all use that capture.