fix: Pass Git actor name to release workflow

[BYK]

Summary

• Pass github.actor as git_user_name to the dogfooding release action so Craft has a Git commit author.
• Add a regression that checks the workflow input.

Validation

• Frozen pnpm installs passed for root and docs.
• Full Vitest suite passed: 62 files, 1,260 passed, 1 skipped.
• Focused action tests passed: 55 tests.
• Typecheck, lint, format check, root build, and docs build passed (29 pages).