Fix controlled-failure crash in run skill

The run skill raised RuntimeError for scenario=controlled-failure,
causing HTTP500. Return the safe recovered result instead and add
regression coverage.

tests/test_agent.py

@@ -12,6 +12,9 @@ async def test_controlled_failure_has_a_safe_result() -> None:
     agent = SelfHealingDemo()
     ctx = LocalRunContext(auth=NoAuth())
 
+    # Regression: this scenario previously raised
+    # RuntimeError("SELF_HEAL_SMOKE: controlled invoice total handler crashed").
+    # It must now return a safe, recovered result without raising.
     result = await agent.run(ctx, scenario="controlled-failure")
 
     assert result == {
@@ -19,3 +22,13 @@ async def test_controlled_failure_has_a_safe_result() -> None:
         "scenario": "controlled-failure",
         "result": "recovered",
     }
+
+
+@pytest.mark.asyncio
+async def test_normal_scenario_stays_healthy() -> None:
+    agent = SelfHealingDemo()
+    ctx = LocalRunContext(auth=NoAuth())
+
+    result = await agent.run(ctx, scenario="normal")
+
+    assert result == {"ok": True, "scenario": "normal", "result": "healthy"}