chore: Halkyon Todo's scaffold joins the repository in apps/todo

Its server, client and app as `serverpod create` made them, with the
switch to server-side sessions that was waiting uncommitted, as files:
its one commit holds the scaffold alone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/todo/halkyon_todo_server/lib/src/cache_busting.dart

@@ -0,0 +1,10 @@
+import 'dart:io';
+
+import 'package:serverpod/serverpod.dart';
+
+/// Cache busting configuration.
+/// Used in WidgetRoutes to cache-bust asset paths.
+final cacheBustingConfig = CacheBustingConfig(
+  mountPrefix: '/web',
+  fileSystemRoot: Directory(Uri(path: 'web/static').toFilePath()),
+);