fix(library): keep the shell the deploy replaced out of a failed navigation, and say when another tab holds the library open

docker/frontend/src/i18n/en.ts

@@ -296,6 +296,8 @@ export const en: Dict = {
   'lib.scanned': 'Scanned {folder}: {added}/{total} new frames.',
   'lib.empty': 'Nothing in this folder yet.',
   'lib.noFolders': 'No folder yet. Hit ADD FOLDER and pick a photo folder on this machine.',
+  'lib.blocked':
+    'Another tab of this app is holding the library open from an older build. Close that tab, or reload it, and this one picks the library up.',
   'lib.missing': 'Could not open {name} — the file has been moved or deleted.',
   'lib.failed': 'That folder could not be read.',
   'lib.unsupported':