test(issue-5): harden watcher evidence validation and add codex pass review report

- Enforce evidence-root confinement for capture_ref and 1:1 capture citation uniqueness
- Add pane identity and backend identity cross-validation
- Add bidirectional agreement checks between watcher/herdr manifests and scenario fixtures
- Expand contract test suite to 41 tests (100% pass)
- Document evidence confinement rules in herdr-runtime.md and update task.md
- Archive Codex 4th review report (Job 1bd561e6: [VERDICT: PASS])

docs/contracts/issue-5/baseline.md

@@ -4,7 +4,7 @@
 - **Issue**: [Gitea Issue #5 — `[Refactor] lib.sh 작업 위임 로직 및 run_loop.sh 오케스트레이터의 Python 모듈화 (lib_py 승격)`](https://git.godopu.com/tmpl/multi-agent-mux/issues/5)
 - **Baseline Commit**: `47640e2fd7b108be29446a9384a343727e87edf8`
 - **Environment Baseline**: Python 3.9.6, Herdr 0.8.2, macOS Darwin 24.3.0
-- **Test Suite Baseline**: 469 tests collected initially; 499 tests collected with Phase 0 contract suite (+30 contract & mutation tests)
+- **Test Suite Baseline**: 469 tests collected initially; 510 tests collected with Phase 0 contract suite (+41 contract & mutation tests)
 - **Status**: Phase 0 Baseline Contract (Observed vs. Proposed vs. Gap)
 
 ---