fix(test): resolve ambiguous behave step in combined branch merge

features/plan_diff_artifacts.feature

@@ -95,7 +95,7 @@ Feature: Plan Diff and Artifacts Output
   Scenario: Merge failure triggers error state
     Given a plan in apply processing state
     When a merge failure occurs with conflict details
-    Then the plan should be in errored state
+    Then the plan should be in an errored processing state
     And the plan error message should contain merge conflict info
     And the plan metadata should contain merge_conflict details
     And the plan metadata should contain sandbox_rollback pending

features/steps/plan_diff_artifacts_steps.py

@@ -460,7 +460,7 @@ def step_metadata_timestamp(context: Context) -> None:
     assert "apply_completed_at" in plan.error_details
 
 
-@then("the plan should be in errored state")
+@then("the plan should be in an errored processing state")
 def step_plan_errored(context: Context) -> None:
     plan = context.lifecycle_service.get_plan(context.plan_id)
     assert plan.processing_state == ProcessingState.ERRORED