Add task lifecycle tests

tests/test_task_lifecycle.py

@@ -0,0 +1,17 @@
+from active_runtime.app.task_lifecycle import TaskLifecycle
+
+
+def test_owner_approval_button_appears_for_waiting_task():
+    lifecycle = TaskLifecycle()
+    actions = lifecycle.available_actions({"task_id": "t1", "status": "waiting_approval"}, "owner")
+    approve = [a for a in actions if a["action"] == "approve"][0]
+    assert approve["enabled"] is True
+
+
+def test_block_requires_reason():
+    lifecycle = TaskLifecycle()
+    try:
+        lifecycle.transition({"status": "running"}, "block", "executor")
+        assert False
+    except ValueError:
+        assert True