Add copilot-setup-steps.yml for workspace setup (#2524)

Download dependencies so they are available in coding agents. Otherwise, the coding agents are unable to access pkg.pr.new and pkg.vc domains so the package install fails.

Author: Copilot

.github/workflows/copilot-setup-steps.yml

@@ -0,0 +1,28 @@
+name: Copilot Setup Steps
+
+# Automatically run the setup steps when they are changed to allow for easy validation, and
+# allow manual testing through the repository's "Actions" tab
+on:
+    workflow_dispatch:
+    push:
+        paths:
+            - .github/workflows/copilot-setup-steps.yml
+    pull_request:
+        paths:
+            - .github/workflows/copilot-setup-steps.yml
+
+jobs:
+    copilot-setup-steps:
+        runs-on: ubuntu-latest
+        permissions:
+            contents: read
+        steps:
+            - uses: actions/checkout@v5
+            - name: Use Node.js
+              uses: actions/setup-node@v6
+              with:
+                  node-version: 20
+            - name: Install pnpm
+              uses: pnpm/action-setup@v4
+            - name: Install dependencies
+              run: pnpm install --frozen-lockfile