add offline support

public/js/bootstrap-loader.js

@@ -144,8 +144,9 @@
   }
 
   function openApplication(event) {
-    if (!ready || !isActivation(event)) return;
+    if (!ready || globalThis.Wegwichtel.OfflineCache?.busy || !isActivation(event)) return;
     if (event.target !== enter && event.target.closest('button, input, label, a, dialog')) return;
+    if (event.target.closest('.offline-help, .storage-usage')) return;
 
     event.preventDefault();
     event.stopPropagation?.();
@@ -192,6 +193,7 @@
     }
 
     try {
+      await globalThis.Wegwichtel.OfflineCache?.initialize();
       setStatusText(stepLabels.storage, true);
       await cleanupOldProgress();
       mark('storage', 'done');