[BYK]

Summary

• Allow only Git author/committer identity variables through simple-git 4's environment guard in Craft Git clients.
• Keep other guarded Git environment variables blocked.
• Add a real-Git regression that creates a commit through getGitClient() with no configured identity, and update the clone client assertion.

The dogfooding release already supplies GIT_AUTHOR_NAME and related identity variables, but simple-git 4 strips them by default. This caused the release commit to fail with an empty author name.

Validation

• pnpm test -- --printConsoleTrace (62 files; 1,261 passed, 1 skipped)
• pnpm typecheck
• pnpm lint
• pnpm format:check
• pnpm build (source-map upload skipped because SENTRY_AUTH_TOKEN is unset)
• pnpm docs:build (29 pages)