Update docker image to Node 22

[SarthakDudhe]

Summary

• update the Docker image base from node:20-alpine to node:22-alpine
• align the published Docker image with the package's supported Node runtime
• update the Docker image foundation test to expect Node 22

Closes #1798

Testing

• Verified the Docker image and tests were still pinned to Node 20 before the change
• Full Docker build/test could not be completed in this session because the local Docker engine was not running and Python/testinfra was not available in the shell