build(deps): bump node to v22 (LTS)

[benelan]

Summary

• Bump Node to LTS, which is now v22
• Add an .nvmrc version file to prevent conflicts with volta

Note

This causes a github-script warning during npm install, which can be ignored since the package is only used for types.

npm warn EBADENGINE Unsupported engine {
npm warn EBADENGINE   package: '[email protected]',
npm warn EBADENGINE   required: { node: '>=20.0.0 <21.0.0' },
npm warn EBADENGINE   current: { node: 'v22.13.0', npm: '10.9.2' }
npm warn EBADENGINE }