fix(review-helm): propagate required cleanup failures

Scope

Partial delivery for #434 (closed) and Runner owner feedback. This MR does not complete generic lifecycle extraction or adapt the Runner consumer.

Plan

1. Remove unconditional suppression of generic Helm release cleanup failures.
2. Keep missing releases idempotent after failed startup, preserving diagnostics and runtime cleanup.
3. Verify the actual expanded stop script with local regressions, then required exact-source CI before review.

Acceptance criteria

• Successful uninstall and an absent release succeed.
• Permission and transport failures propagate their original nonzero status.
• Diagnostics precede uninstall; runtime cleanup executes on success and failure.
• New regression fails on unchanged main, which incorrectly returns success on a simulated uninstall error.
• Existing diagnostic-replay regression, all seven metrics-readiness cases, syntax, whitespace and root CI YAML lint pass locally.
• Required exact-source CI executes the new regression and passes.
• Live review namespace teardown and the focused final DoD are verified.

The catalog Bash component discovers *.ci-test.sh recursively, including this new script. Exact-source CI succeeds across all 62 root/downstream pipelines: 217 jobs pass and five pre-existing allow-failure jobs fail; no required jobs fail. The focused regression executes all four cleanup scenarios in CI. Live review teardown confirms diagnostics and namespace deletion with create-namespace: true; the changed existing-namespace uninstall branch is covered by executed mocks, not claimed as a separate live Helm uninstall. The final two-file diff is reviewed and rebase on current main is a no-op. No source or CI configuration changed during final verification. Local ShellCheck is unavailable. No Runner component pin, image digest, chart location, reviewer or owner discussion is changed. Shared metrics readiness and safe diagnostic display already exist on main and must be reused by the broader #434 (closed) implementation.

Related to #434 (closed). Keep #434 (closed) open after this focused fix.