implemented file search with local cache and server-side support, added result highlighting, and integrated search delegate into files page

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

@@ -14,13 +14,25 @@ import '../../../../widget/centered_leading.dart';
 import '../../../../widget/confirm_dialog.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../../../../widget/info_dialog.dart';
+import '../../talk/widgets/highlighted_linkify.dart';
 import 'file_details_sheet.dart';
 
 class FileElement extends StatefulWidget {
   final CacheableFile file;
   final List<String> path;
   final void Function() refetch;
-  const FileElement(this.file, this.path, this.refetch, {super.key});
+
+  /// When non-null, occurrences of this string in the file name are visually
+  /// highlighted in the tile title. Used by the Files search delegate.
+  final String? highlight;
+
+  const FileElement(
+    this.file,
+    this.path,
+    this.refetch, {
+    this.highlight,
+    super.key,
+  });
 
   @override
   State<FileElement> createState() => _FileElementState();
@@ -118,7 +130,7 @@ class _FileElementState extends State<FileElement> {
     );
   }
 
-  Widget _subtitle() {
+  Widget? _subtitle() {
     final status = _job?.status.value;
     if (status is DownloadInProgress) {
       return Row(
@@ -135,10 +147,16 @@ class _FileElementState extends State<FileElement> {
         ],
       );
     }
-    final modified = widget.file.modifiedAt ?? DateTime.now();
-    return widget.file.isDirectory
-        ? Text('geändert ${modified.formatRelative()}')
-        : Text('${filesize(widget.file.size)}, ${modified.formatRelative()}');
+    final modified = widget.file.modifiedAt;
+    final size = widget.file.size;
+    if (widget.file.isDirectory) {
+      if (modified == null) return null;
+      return Text('geändert ${modified.formatRelative()}');
+    }
+    if (size == null && modified == null) return null;
+    if (size == null) return Text(modified!.formatRelative());
+    if (modified == null) return Text(filesize(size));
+    return Text('${filesize(size)}, ${modified.formatRelative()}');
   }
 
   void _onTap() {
@@ -328,12 +346,36 @@ class _FileElementState extends State<FileElement> {
     );
   }
 
+  Widget _title(BuildContext context) {
+    final base =
+        Theme.of(context).textTheme.bodyLarge ??
+        DefaultTextStyle.of(context).style;
+    if (widget.highlight == null || widget.highlight!.trim().isEmpty) {
+      return Text(
+        widget.file.name,
+        maxLines: 2,
+        overflow: TextOverflow.ellipsis,
+      );
+    }
+    return Text.rich(
+      TextSpan(
+        children: buildHighlightedSpans(
+          text: widget.file.name,
+          query: widget.highlight,
+          baseStyle: base,
+        ),
+      ),
+      maxLines: 2,
+      overflow: TextOverflow.ellipsis,
+    );
+  }
+
   @override
   Widget build(BuildContext context) => ListTile(
     leading: CenteredLeading(
       Icon(widget.file.isDirectory ? Icons.folder : Icons.description_outlined),
     ),
-    title: Text(widget.file.name, maxLines: 2, overflow: TextOverflow.ellipsis),
+    title: _title(context),
     subtitle: _subtitle(),
     trailing: Icon(widget.file.isDirectory ? Icons.arrow_right : null),
     onTap: _onTap,