feat(bm-import): Import-Modal mit View-Transition-Fade, Teardown in Closure

src/js/bookmark-import.js

@@ -4,6 +4,20 @@
    via chrome.bookmarks.getTree() / browser.bookmarks.getTree()
    ============================================= */
 
+/**
+ * Fuehrt eine DOM-Mutation mit nativem View-Transition-Fade aus.
+ * Feature-Detection-Fallback (Firefox < 144): instant.
+ * reduced-motion kappt das Fade ueber den ungeschichteten @media-Block.
+ * @param {Function} mutate - synchrone DOM-Mutation
+ */
+function bmImportViewTransition(mutate) {
+  if (document.startViewTransition) {
+    document.startViewTransition(mutate);
+  } else {
+    mutate();
+  }
+}
+
 const BrowserBookmarkImport = {
 
   /** Initialisiert den Import-Button */
@@ -196,16 +210,18 @@ const BrowserBookmarkImport = {
     overlay.appendChild(modal);
     document.body.appendChild(overlay);
 
-    // Animation
-    requestAnimationFrame(() => overlay.classList.add('active'));
+    // View-Transition-Fade
+    bmImportViewTransition(() => overlay.classList.add('active'));
   },
 
   /** Schliesst das Modal */
   _closeModal() {
     const overlay = document.getElementById('bmImportOverlay');
     if (!overlay) return;
+    bmImportViewTransition(() => {
       overlay.classList.remove('active');
-    setTimeout(() => overlay.remove(), 250);
+      overlay.remove();
+    });
   },
 
   /**