fix(mma): Use headless execution flag for context amnesia and parse json output

tests/test_mma_exec.py

@@ -64,7 +64,8 @@ def test_execute_agent():
         cmd_list = args[0]
         
         assert cmd_list[0] == "gemini"
-        assert cmd_list[1] == expected_gemini_arg
+        assert cmd_list[1] == "-p"
+        assert cmd_list[2] == expected_gemini_arg
         assert kwargs.get("capture_output") is True
         assert kwargs.get("text") is True