chore(tech-debt): Finalize gui_2.py cleanup and test suite discipline

tests/test_execution_engine.py

@@ -1,3 +1,4 @@
+import pytest
 from models import Ticket
 from dag_engine import TrackDAG, ExecutionEngine
 
@@ -42,6 +43,7 @@ def test_execution_engine_update_nonexistent_task() -> None:
  engine = ExecutionEngine(dag)
  # Should not raise error, or handle gracefully
  engine.update_task_status("NONEXISTENT", "completed")
+ pytest.fail("TODO: Implement assertions")
 
 def test_execution_engine_status_persistence() -> None:
  t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")