chat search now lists local and server-side hits like the file search, and jumping to old messages pages in history with a progress banner and keeps the hit marked

lib/view/pages/talk/search/chat_search_delegate.dart

@@ -0,0 +1,49 @@
+import 'package:flutter/material.dart';
+
+import '../data/chat_message_matcher.dart';
+import 'chat_search_controller.dart';
+import 'chat_search_results.dart';
+
+/// Search inside one chat, built like `FilesSearchDelegate`. Closes with the
+/// tapped hit so the chat can jump there.
+class ChatSearchDelegate extends SearchDelegate<ChatSearchHit?> {
+  final ChatSearchController _controller;
+
+  ChatSearchDelegate(this._controller)
+    : super(searchFieldLabel: 'In Chat suchen');
+
+  /// Must be called by the host widget after `showSearch` returns so the
+  /// controller's listeners and pending debounce timers are released.
+  void disposeController() => _controller.dispose();
+
+  @override
+  List<Widget>? buildActions(BuildContext context) => [
+    if (query.isNotEmpty)
+      IconButton(
+        tooltip: 'Suche leeren',
+        icon: const Icon(Icons.clear),
+        onPressed: () {
+          query = '';
+        },
+      ),
+  ];
+
+  @override
+  Widget? buildLeading(BuildContext context) => IconButton(
+    icon: const Icon(Icons.arrow_back),
+    tooltip: 'Zurück',
+    onPressed: () => close(context, null),
+  );
+
+  @override
+  Widget buildResults(BuildContext context) => buildSuggestions(context);
+
+  @override
+  Widget buildSuggestions(BuildContext context) {
+    _controller.setQuery(query);
+    return ChatSearchResults(
+      controller: _controller,
+      onResultTap: (hit) => close(context, hit),
+    );
+  }
+}