fix(api): constrain shopping suggestion enums

backend/tests/test_products_helpers.py

@@ -121,6 +121,14 @@ def test_suggest_shopping(client, session):
         assert data["reasoning"] == "Test shopping"
         kwargs = mock_gemini.call_args.kwargs
         assert "USER PROFILE:" in kwargs["contents"]
+        assert (
+            'category: "cleanser" | "toner" | "essence"'
+            in kwargs["config"].system_instruction
+        )
+        assert (
+            'recommended_time: "am" | "pm" | "both"'
+            in kwargs["config"].system_instruction
+        )
         assert "function_handlers" in kwargs
         assert "get_product_details" in kwargs["function_handlers"]