fix(tests): resolve ambiguous step definition in persona state coverage tests

- Rename duplicate step 'the registry last persona should be set to' to 'the mock registry last persona should be set to' in tui_persona_state_coverage_steps.py
- Update corresponding feature file to use the new step name
- Fixes AmbiguousStep error that was preventing unit tests from running

features/steps/tui_persona_state_coverage_steps.py

@@ -236,7 +236,7 @@ def step_verify_session_active_persona(context, session_id, expected):
     assert context.state.active_by_session[session_id] == expected
 
 
-@then('the registry last persona should be set to "{expected}"')
+@then('the mock registry last persona should be set to "{expected}"')
 def step_verify_last_persona_set(context, expected):
     context.mock_registry.set_last_persona.assert_called_with(expected)
 

features/tui_persona_state_coverage.feature

@@ -33,7 +33,7 @@ Feature: TUI Persona State Coverage
     When I set persona "coder" for session "sess-6"
     Then the returned persona name should be "coder"
     And session "sess-6" should have active persona "coder"
-    And the registry last persona should be set to "coder"
+    And the mock registry last persona should be set to "coder"
 
   Scenario: set_active_persona skips preset init when session already has one
     Given the preset for session "sess-6b" is already set to "turbo"