fix(ci): add Node 22 for copilot CLI compatibility

Copilot's runtime package blob may require Node 22+. The default
ubuntu-latest runner ships Node 20 which causes SyntaxError on
the downloaded index.js.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: christso

.github/workflows/evals.yml

@@ -26,6 +26,9 @@ jobs:
       models: read
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
       - uses: ./.github/actions/setup-bun
 
       - name: Build