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/bin/main.dart

@@ -0,0 +1,7 @@
+import 'package:halkyon_todo_server/server.dart';
+
+/// This is the starting point for your Serverpod server. Typically, there is
+/// no need to modify this file.
+void main(List<String> args) {
+  run(args);
+}