[Plan Deliverables Must Exist] Enforce plan deliverable review gates

[lossyrob]

Closes #282

Summary

• make paw-implement verify current-phase Changes Required deliverables before marking a phase complete
• make paw-impl-review compare planned deliverables against actual repo state and block missing or empty planned outputs
• make paw-final-review and the implementation spec treat missing planned deliverables as substantive review findings

Testing

• ./scripts/lint-prompting.sh skills/paw-implement/SKILL.md
• ./scripts/lint-prompting.sh skills/paw-impl-review/SKILL.md
• ./scripts/lint-prompting.sh skills/paw-final-review/SKILL.md
• npm run lint
• npm run compile
• cd tests/integration && npx tsx --test tests/skills/plan-deliverable-guardrails.test.ts
• cd tests/integration && npx tsc --noEmit -p tsconfig.json
• docs build could not run locally because .venv/bin/activate was not present in this worktree

Artifacts

• PAW work artifacts (last tracked commit): https://github.com/lossyrob/phased-agent-workflow/tree/922dfe3005b838fc8dfb1da91723c63f8b040396/.paw/work/plan-deliverable-verification

Reviewer Notes

• focus on the deliverable-contract language across paw-implement, paw-impl-review, and paw-final-review
• the new regression test is offline-only and locks the prompt/spec contract in place

🐾 Generated with PAW