Retire exercise_status: maturity is the only notion; add CLI tests (RBT-WP-0009-T01)

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

tests/test_showcase.py

@@ -35,8 +35,8 @@ def test_scripted_playthrough(pk):
         R.complete(r, sid, {n: "1" for n in s.get("evidence", [])})
     assert r.complete
     assert not Path(r.data["params"]["logdir"]).exists()
-    old, new = R.exercise_update(r)
-    assert "exercised" in new
+    R.finalize(r, "succeeded")                                     # every step done: the run may succeed
+    assert r.data["outcome"] == "succeeded"
 
 
 def test_bad_logdir_rejected(pk):