implemented file thumbnails and enhanced file type icons, added reusable FileLeading widget, and updated search to support previews

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

@@ -5,6 +5,7 @@ import '../../../../api/marianumcloud/webdav/queries/list_files/cacheable_file.d
 import '../../../../extensions/date_time.dart';
 import '../../../../utils/clipboard_helper.dart';
 import '../../../../widget/details_bottom_sheet.dart';
+import 'file_leading.dart';
 
 /// Shows a modal bottom sheet with technical metadata about a single file or
 /// folder: full path, MIME type, size, timestamps, ETag.
@@ -12,10 +13,7 @@ void showFileDetailsSheet(BuildContext context, CacheableFile file) {
   showDetailsBottomSheet(
     context,
     header: ListTile(
-      leading: Icon(
-        file.isDirectory ? Icons.folder : Icons.description_outlined,
-        size: 32,
-      ),
+      leading: FileLeading(file: file, size: 40),
       title: Text(
         file.name,
         style: const TextStyle(fontWeight: FontWeight.bold),