Add a reusable evidence collector for manual transition tier-failure attribution samples and wire the runbook tests to cover its dry-run and argument guards.
Co-authored-by: heihutu <heihutu@gmail.com>
Add a script-test entry for the manual transition rollout and soak runbook generators. The test covers ratio fail-fast behavior, generated status/metrics/journal checks, and runnable dry-run artifacts.
Verification:
- ./scripts/test_manual_transition_runbooks.sh
- make script-tests
Co-authored-by: heihutu <heihutu@gmail.com>