Fix multi-repository PR lifecycle tracking

[eshulman2]

Summary

• make implementation PR lifecycle state authoritative per repository while retaining scalar compatibility fields for existing workflow nodes
• activate the correct repository, PR number, fork, CI state, review state, and lifecycle gate from GitHub webhook identity
• evaluate CI only for the PR that emitted the webhook so failures are repaired in the correct repository
• retain review decisions and contested threads independently for each repository
• require every implementation PR to merge before completing a multi-repository workflow
• preserve compatibility for legacy single-PR checkpoints

Regression coverage

• two created repositories retain independent PR numbers
• CI webhooks for an earlier PR reactivate its repository after another PR reached review
• review feedback targets the earlier PR and workspace
• merging one PR keeps the workflow paused; merging all PRs completes it
• issue comments and check-suite payloads resolve the correct PR
• per-PR lifecycle gates survive interleaved events

Validation

• focused orchestrator, PR creation, CI, review, feature-state, and bug-state test suites
• broader unit workflow/orchestrator and feature integration suites
• Ruff checks and formatting
• git diff --check

Closes #135