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_client/pubspec.yaml

@@ -0,0 +1,11 @@
+name: halkyon_todo_client
+description: Starting point for a Serverpod client.
+
+environment:
+  sdk: '^3.12.2'
+
+resolution: workspace
+
+dependencies:
+  serverpod_auth_idp_client: 4.0.3
+  serverpod_client: 4.0.3