simplified code across the app and consolidated duplicated helpers

lib/view/pages/files/widgets/clipboard_banner.dart

@@ -5,6 +5,7 @@ import '../../../../api/marianumcloud/webdav/queries/list_files/list_files_cache
 import '../../../../api/marianumcloud/webdav/webdav_api.dart';
 import '../../../../utils/file_clipboard.dart';
 import '../../../../widget/info_dialog.dart';
+import '../data/webdav_path.dart';
 
 /// Banner that appears at the top of a Files folder while there is something
 /// in the file clipboard. Shows the cut/copy state and offers a "Hier
@@ -26,16 +27,6 @@ class ClipboardBanner extends StatefulWidget {
 class _ClipboardBannerState extends State<ClipboardBanner> {
   bool _busy = false;
 
-  // All paths here are relative to the WebDAV root (matching `CacheableFile.path`).
-  // Root is the empty string ''. Folders end with '/'.
-  String _normalised(String path) {
-    final stripped = path.replaceAll(RegExp(r'^/+|/+$'), '');
-    return stripped.isEmpty ? '' : '$stripped/';
-  }
-
-  String _joinPath(String folder, String name, {required bool isDirectory}) =>
-      isDirectory ? '$folder$name/' : '$folder$name';
-
   // Disabled when:
   // - clipboard is empty
   // - we'd be pasting a folder into itself or one of its descendants
@@ -43,14 +34,14 @@ class _ClipboardBannerState extends State<ClipboardBanner> {
   bool get _canPaste {
     final cb = FileClipboard.instance;
     if (cb.isEmpty) return false;
-    final dst = _normalised(widget.currentFolder);
+    final dst = webdavFolderPath(webdavSegmentsOf(widget.currentFolder));
     var atLeastOneActionable = false;
     for (final f in cb.files) {
       if (f.isDirectory) {
-        final src = _normalised(f.path);
+        final src = webdavFolderPath(webdavSegmentsOf(f.path));
         if (dst == src || dst.startsWith(src)) return false;
       }
-      final destination = _joinPath(
+      final destination = webdavJoin(
         widget.currentFolder,
         f.name,
         isDirectory: f.isDirectory,
@@ -60,15 +51,6 @@ class _ClipboardBannerState extends State<ClipboardBanner> {
     return atLeastOneActionable;
   }
 
-  // Cache key format used by ListFilesCache (matches FilesBloc's pathString:
-  // relative, no leading or trailing slash; root is '/').
-  String _parentCacheKey(String relativePath) {
-    final stripped = relativePath.replaceAll(RegExp(r'^/+|/+$'), '');
-    if (!stripped.contains('/')) return '/';
-    final parts = stripped.split('/')..removeLast();
-    return parts.isEmpty ? '/' : parts.join('/');
-  }
-
   Future<void> _paste() async {
     final cb = FileClipboard.instance;
     if (_busy || !_canPaste) return;
@@ -79,7 +61,7 @@ class _ClipboardBannerState extends State<ClipboardBanner> {
     try {
       final webdav = await WebdavApi.webdav;
       for (final file in cb.files) {
-        final destination = _joinPath(
+        final destination = webdavJoin(
           widget.currentFolder,
           file.name,
           isDirectory: file.isDirectory,
@@ -91,7 +73,9 @@ class _ClipboardBannerState extends State<ClipboardBanner> {
               PathUri.parse(file.path),
               PathUri.parse(destination),
             );
-            invalidatedSourceFolders.add(_parentCacheKey(file.path));
+            invalidatedSourceFolders.add(
+              listFilesCacheKey(webdavParentSegmentsOf(file.path)),
+            );
           } else {
             await webdav.copy(
               PathUri.parse(file.path),
@@ -105,9 +89,9 @@ class _ClipboardBannerState extends State<ClipboardBanner> {
       // After cut, the source folders no longer contain the moved files. Drop
       // their cached listings so the next visit fetches fresh data instead of
       // briefly showing the moved file as still present.
-      for (final folder in invalidatedSourceFolders) {
-        await ListFilesCache.invalidate(folder);
-      }
+      await Future.wait(
+        invalidatedSourceFolders.map(ListFilesCache.invalidate),
+      );
       if (operation == FileClipboardOperation.cut) cb.clear();
       widget.onPasteDone();
     } finally {