Add actions/setup-node to esm-lint Pack job only

- Added actions/setup-node@v6 with node-version-file: package.json to the Pack job in esm-lint.yml
- This ensures the Pack job uses Node 22.18+ as required for native TypeScript execution
- Other jobs in esm-lint.yml remain unchanged as they download the pre-built artifact
- Lint job in ci.yml already has setup-node configured correctly

Co-authored-by: fregante <1402241+fregante@users.noreply.github.com>

Author: Copilot

.github/workflows/esm-lint.yml

@@ -19,6 +19,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
+        with:
+          node-version-file: package.json
       - run: npm install
       - run: npm run build --if-present
       - run: npm pack --dry-run