Fix CI/local Node version differences causing Prettier inconsistencies

- Update CI workflow to use Node 22 instead of Node 20 to match local development environment
- Add .nvmrc file to pin Node version for consistent development across team

This resolves the issue where CI Prettier checks fail while local checks pass,
caused by different Node versions processing files differently.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

.github/workflows/lint-js-and-ruby.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v4
         with:
-          node-version: 20
+          node-version: 22
           cache: yarn
           cache-dependency-path: '**/yarn.lock'
       - name: Print system information

.nvmrc

@@ -0,0 +1 @@
+22.12.0