- Reduce from 254 to 116 lines by removing per-language jobs
- Add prepare job to centralize input parsing and outputs
- Remove 'grid' as separate option (java:release includes grid via java:package)
- Use single nightly-release job with ./go {lang}:release nightly
- release-grid runs only when artifact-name is set (all/java)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Move the nightly-specific npm configuration from the workflow into the
rake task. This configures:
- GitHub Packages registry and auth token via ~/.npmrc
- Package name change to @seleniumhq/selenium-webdriver
- Registry URL change to npm.pkg.github.com

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>