Provides:
- Recommended merge order (P0 → P1 → P2 → P3 by cluster)
- Per-cluster merge prerequisites and validation steps
- Conflict risk assessment (Cluster 2 #122/#122b have same edit locus)
- Post-merge validation checklist (build + test + dogfood)
- Timeline estimate (~60 min for full 17-branch queue)
Addresses the final integration step: once branches are reviewed, knowing
the safe merge order matters. This artifact pre-answers that question.
Applied doctrine: integration-support artifacts (cycle #64) reduce reviewer
friction. At 17-branch saturation, a merge-safe checklist is first-class work.
Relates to cycle #70 integration throughput initiative.
