Enhance /gsd:pause-work to write .planning/HANDOFF.json alongside
.continue-here.md. The JSON provides machine-readable state that
/gsd:resume-work can parse for precise resumption.
HANDOFF.json includes:
- Task position (phase, plan, task number, status)
- Completed and remaining tasks with commit hashes
- Blockers with type classification (technical/human_action/external)
- Human actions pending (API keys, approvals, manual testing)
- Uncommitted files list
- Context notes for mental model restoration
Resume-work changes:
- HANDOFF.json is primary resumption source (highest priority)
- Surfaces blockers and human actions immediately on session start
- Validates uncommitted files against git status
- Deletes HANDOFF.json after successful resumption
- Falls back to .continue-here.md if no JSON exists
Also checks for placeholder content in SUMMARY.md files to catch
false completions (frontmatter claims complete but body has TBD).
Fixes#940
f54f3df776