chore(tooling): install GUT v9.6.0 test framework

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

addons/gut/double_templates/function_template.txt

@@ -0,0 +1,9 @@
+{func_decleration}
+	if(__gutdbl == null):
+		return
+
+	__gutdbl.spy_on('{method_name}', {param_array})
+	if(__gutdbl.is_stubbed_to_call_super('{method_name}', {param_array})):
+		{super_call}
+	else:
+		return await __gutdbl.handle_other_stubs('{method_name}', {param_array})