fix(images): describe transforms by the Viewer.js an image was built with

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.

web/js/workspace/media-viewer.mjs

@@ -35,7 +35,7 @@ export function createMediaViewer({api,container,parentScope,inspectionControlle
         if (scope.signal.aborted) return;
         active?.close(false);
         const {items,selectedKey,trigger = document.activeElement} = options;
-        let mounted = false, initial, entry, currentKey, viewer = null, mediaScope = null, closed = false;
+        let mounted = false, initial, entry, currentKey, viewer = null, withoutViewer = false, mediaScope = null, closed = false;
         let originalDownload = null, inspectionState = inspectionController.state;
         const session = createViewerSession({adapter,items,initialKey:selectedKey,onChange:(state,selected) => {
             if (!mounted) { initial = [state,selected]; return; }
@@ -115,7 +115,9 @@ export function createMediaViewer({api,container,parentScope,inspectionControlle
             mediaScope?.dispose();mediaScope = createScope();viewer = null;
             for (const child of [...stage.children]) if (child !== failure) child.remove();
             failure.hidden = true;
-            const mediaLocal = mediaScope, key = session.state.key;
+            const mediaLocal = mediaScope, key = session.state.key, ViewerJs = window.Viewer;
+            // Transforms follow the Viewer.js this media was built with, which builds once the image has loaded.
+            withoutViewer = !ViewerJs;
             const current = () => !local.signal.aborted && !mediaLocal.signal.aborted && session.state.key === key;
             // An adapter's own media URL (a session-owned blob:) is used exactly, so a retry reuses it; a server
             // original gets a fresh cache-buster on every build.
@@ -142,15 +144,15 @@ export function createMediaViewer({api,container,parentScope,inspectionControlle
                 },{once:true});
             } else {
                 node.alt = selected.filename;node.decoding = 'async';
-                node.hidden = !!window.Viewer;
+                node.hidden = !!ViewerJs;
                 // With Viewer.js the src is released after the viewer (see release below).
-                if (!window.Viewer) {
+                if (!ViewerJs) {
                     mediaLocal.listen(node,'load',() => {if (current()) session.ready(key);});
                     mediaLocal.cleanup(() => node.removeAttribute('src'));
                 }
             }
             node.src = src;stage.append(node);
-            if (!selected.is_video && window.Viewer) {
+            if (!selected.is_video && ViewerJs) {
                 // Viewer.js is built on an image that has loaded. Its own cancel removes its image listeners only
                 // while `image.complete` is false, so an image left with its load event still queued would build a
                 // viewer into the released image after destroy() (#293). Until then no viewer exists to cancel.
@@ -174,7 +176,7 @@ export function createMediaViewer({api,container,parentScope,inspectionControlle
                         fitWidth = width;fitHeight = height;instance.resize();
                     });
                 };
-                const instance = new window.Viewer(node,{inline:true,toolbar:false,navbar:false,title:false,button:false,
+                const instance = new ViewerJs(node,{inline:true,toolbar:false,navbar:false,title:false,button:false,
                     keyboard:false,fullscreen:false,transition:false,viewed() {
                         viewSettled = true;
                         if (mediaLocal.signal.aborted) { release(); return; }
@@ -198,7 +200,7 @@ export function createMediaViewer({api,container,parentScope,inspectionControlle
         }
         function updateControls(state) {
             const unavailable = inspectionState.refreshRequired ? inspectionState.message : state.phase === 'error' ? 'Media could not be loaded. Retry this file.' : entry.is_video ?
-                'Image transforms are unavailable for video.' : !window.Viewer ?
+                'Image transforms are unavailable for video.' : withoutViewer ?
                 'Image transforms are unavailable because Viewer.js could not load.' : !state.mediaReady ? 'Image transforms are available when the image is ready.' : '';
             reason.textContent = unavailable;reason.hidden = !unavailable;
             for (const node of transforms) {