[Unit PRs] Complete required skeleton and batch reviews before PR readiness #559

Part of #553. Suggested step 5 of 13; one focused PR into main.

Outcome: A unit-to-base PR cannot become ready through the platform until the required stage, skeleton and batch reviews governing its publication are satisfied.

Depends on: #555, #558

Scope

• Move the applicable walking-skeleton and batch review boundary before publication readiness for the new policy only, using the selected effective workflow plan.
• Request-changes revises unmerged unit work and reruns affected sensors/checks. Preserve existing autonomy modes, recorded answers, park/resume and the ordinary stage approval contract.
• Separate successful lane preparation from delivered integration so the review loop does not require the work to be merged first.
• Require current run/attempt and reviewed-head identity at readiness; preserve old history paths and old strategy gate ordering.

Acceptance criteria

• Skeleton and gated-batch fixtures cannot mark a PR ready before their required approvals.
• Request-changes keeps work unpublished and re-asks only the appropriate gate after revision and validation.
• Autonomous and skeleton-off modes preserve their selected policy without acquiring a blanket new approval gate.
• Stale callback, revised head, failed sensor and superseded plan cannot reuse an earlier approval incorrectly.
• Focused orchestration/park-resume and frozen-history replay tests pass; readiness authorization remains distinct from external provider merge permissions.

PR boundary and rollout

Pre-publication gate ordering and revision semantics only. No provider merge authority, named-reviewer rules, branch-protection edits, tracker changes, or automatic rollback after an external merge.

Starting points

lambda/v2-orchestrator/section.js, lambda/v2-orchestrator/index.js, lambda/shared/v2-process-store.js.

Planning baseline: main at b5d68d5d2f12292d56a21aab917e4d8f9538aa0b (2026-10-15). Recheck current main and applicable guidance before implementation. Existing strategies remain supported; the new capability stays disabled until qualification.