fixed overwrite on internal copy, DST drift in widget anchors, inline errors without controller and removed dead room lookup

lib/view/pages/talk/details/chat_info.dart

@@ -108,16 +108,11 @@ class _ChatInfoState extends State<ChatInfo> {
     if (result == null || !mounted) return;
 
     if (result is AvatarRemoveResult) {
-      var confirmed = false;
-      await showDialog<void>(
-        context: context,
-        builder: (_) => ConfirmDialog(
-          title: 'Gruppenbild entfernen',
-          content: 'Möchtest du das Gruppenbild wirklich entfernen?',
-          confirmButton: 'Entfernen',
-          onConfirm: () => confirmed = true,
-        ),
-      );
+      final confirmed = await const ConfirmDialog(
+        title: 'Gruppenbild entfernen',
+        content: 'Möchtest du das Gruppenbild wirklich entfernen?',
+        confirmButton: 'Entfernen',
+      ).ask(context);
       if (!confirmed || !mounted) return;
     }