fix(tests): update mock SessionReady with resumed + history fields

sunbeam/tests/code_integration.rs

@@ -38,6 +38,8 @@ impl CodeAgent for MockCodeAgent {
                             } else {
                                 start.model
                             },
+                            resumed: false,
+                            history: vec![],
                         })),
                     })).await;
                 }