impl: fall back to CODER_HEADER_COMMAND when the header command setting is blank - #600

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: gradle/actions/wrapper-validation@v3.5.0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Failed to save: "C:\Program failed with error: The process 'C:\Program Files\Git\usr\bin\tar.exe' failed with exit code 2