l10n: localize settings, store, and metadata UI strings

Wire remaining hardcoded strings in about, download region picker, file
organization settings, extension repo snackbars, release type badges,
metadata queue actions, online cover labels, and update changelog fallback.

lib/widgets/update_dialog.dart

@@ -223,7 +223,10 @@ class _UpdateDialogState extends State<UpdateDialog> {
                 child: SingleChildScrollView(
                   padding: const EdgeInsets.all(16),
                   child: Text(
-                    _formatChangelog(widget.updateInfo.changelog),
+                    _formatChangelog(
+                      widget.updateInfo.changelog,
+                      context.l10n.updateSeeReleaseNotes,
+                    ),
                     style: Theme.of(context).textTheme.bodySmall?.copyWith(height: 1.5),
                   ),
                 ),
@@ -299,7 +302,7 @@ class _UpdateDialogState extends State<UpdateDialog> {
   }
 
   /// Format changelog - clean up markdown and extract relevant content
-  String _formatChangelog(String changelog) {
+  String _formatChangelog(String changelog, String emptyFallback) {
     var content = changelog;
     
     final whatsNewMatch = _whatsNewPattern.firstMatch(content);
@@ -352,7 +355,7 @@ class _UpdateDialogState extends State<UpdateDialog> {
       formatted = '${formatted.substring(0, 2000)}...';
     }
     
-    return formatted.isEmpty ? 'See release notes for details.' : formatted;
+    return formatted.isEmpty ? emptyFallback : formatted;
   }
 }