fix: ensure Node.js is available in copilot-setup-steps for GPU runners (#2228)

* Initial plan

* fix: add setup-node to copilot-setup-steps to guard Node.js on GPU runners

Agent-Logs-Url: https://github.com/github/gh-aw-firewall/sessions/a19baeac-bd68-4fd3-be96-e3f40f0d35bc

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Author: Copilot

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

@@ -18,6 +18,13 @@ jobs:
       contents: read
 
     steps:
+      # Ensure Node.js is available on all runner types (including GPU runners
+      # where it may not be pre-installed). Copilot engine workflows require
+      # Node.js to invoke the Copilot CLI binary.
+      - name: Set up Node.js
+        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        with:
+          node-version: '20'
       - name: Install gh-aw extension
         run: |
           curl -fsSL https://raw.githubusercontent.com/github/gh-aw/refs/heads/main/install-gh-aw.sh | bash