Add lighthouse showcase pack (v0.1 runnable, v0.2 draft); fix manual-check cycle and blocked-step feedback (RBT-WP-0004-T05)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: sonnet
Assistant-Process: 295952@bnt-lap001
Assistant-Session: e93f64ad-516c-46eb-9666-aad8d300c477

README.md

@@ -6,7 +6,8 @@ can guide through actual IT administration and operation tasks.
 - **Intent:** `INTENT.md` · **Scope:** `SCOPE.md`
 - **Pack specification:** `docs/pack-spec.md`, schema in `schema/`
 - **Packs live where the procedure lives:** `runbooks/<pack>/pack.yaml` in the owning repo.
-  Examples: `net-kingdom/runbooks/`, and `runbooks/example-hello/` here.
+  Examples: `net-kingdom/runbooks/`, and here `runbooks/example-hello/` and
+  `runbooks/showcase-lighthouse/` (a harmless story to try the UI on).
 
 ```bash
 python3 -m rtut validate <repo-root>      # validate every pack