ci: opt-in to Node.js 24 for reusable workflow

Author: jdalton

.github/workflows/ci.yml

@@ -119,6 +119,11 @@ on:
 permissions:
   contents: read
 
+env:
+  # Opt-in to Node.js 24 for GitHub Actions to avoid deprecation warnings.
+  # See: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/
+  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true