fix(review): update test recipe to satisfy sentinel validation rule

The test recipe's stop message 'done' triggers the error-severity
all-dispatchable-stops-have-sentinel rule, causing get_recipe to return
an error instead of valid content. Update the stop message to include
'sentinel' so the recipe passes validation and the restored error-free
assertion holds.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Trecek

tests/server/test_tools_kitchen_gate_features.py

@@ -341,7 +341,7 @@ def test_get_recipe_uses_project_dir(tmp_path, monkeypatch):
         "steps": {
             "stop": {
                 "action": "stop",
-                "message": "done",
+                "message": "Task complete — emit the L3 sentinel block and terminate.",
             },
         },
     }