ci(windows-worker): add push trigger on the prototype branch

Lets the Build Windows Worker workflow auto-run on pushes to
feature/windows-worker-packaging so we can validate the hosted
windows-latest build before merging to main (workflow_dispatch only
registers from the default branch). Keeps workflow_dispatch for later.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 26f310eb-4680-4102-a8aa-f8d041940ab4

Author: andrewkcchung

.github/workflows/build-windows-worker.yml

@@ -8,6 +8,9 @@ name: Build Windows Worker
 # Does not touch the existing Linux publish-npm.yml flow.
 
 on:
+  push:                    # auto-run on this prototype branch so we can see output pre-merge
+    branches:
+      - feature/windows-worker-packaging
   workflow_dispatch:
     inputs:
       build_image: