Refactor workflow-hello-git checkout reuse and helper extraction

[toyamarinyon]

Summary

• reuse an existing workflow-hello-git checkout instead of always deleting and recloning repo
• recover from broken or mismatched checkout state before cloning the expected repository
• extract workflow event writing, report schema/prompt helpers, and artifact collection into focused modules to keep the main workflow legible
• preserve the existing workflow output shape while keeping clonePerformed truthful

Testing

• bun run typecheck

Closes route06/giselle-division#5542

[toyamarinyon]

I'll be try again later