Update PR workflow: CI → UAT (Patty) → QA (Regina) → CTO → merge

Reorder the review pipeline so cheap/fast stages gate expensive ones:
CI (free) runs first, then Patty validates E2E on MiniMax, then
Regina does deep code review on Sonnet, then Nancy reviews last.

- POLICIES.md: rewrite PR Workflow with 6-step ordered pipeline
- Patty SOUL.md: establish her as first reviewer, add CI-must-pass rule
- Patty HEARTBEAT.md: check CI status before E2E, report results for Regina
- Regina SOUL.md: flip from "review first" to "review after UAT"
- Regina HEARTBEAT.md: skip PRs without CI + E2E validation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

engineering/regina/HEARTBEAT.md

@@ -60,6 +60,7 @@ Replace `{issueId}` with the actual issue ID. If checkout returns 409 (already c
 
 For each open PR not yet reviewed by you:
 
+- **Skip if not ready**: Check that CI has passed and Pixel Patty (UAT) has posted an E2E validation comment or approval. If either is missing, skip this PR — it is not ready for your review.
 - Read the diff carefully
 - Check out the branch and run the test suite:
       gh pr checkout <number>