feat(canvas): 绘图工具 - 集成 Excalidraw 并支持后台切换默认引擎

web/src/lib/user-session.ts

@@ -25,6 +25,7 @@ export async function applyUserSession(payload: AuthSessionPayload) {
         const persistedConfig = scopedLocalStorage.getItem(CONFIG_STORE_KEY);
         useUserStore.getState().setUser(payload.user);
         useUserStore.getState().setRuntimeLimits(payload.runtimeLimits);
+        useUserStore.getState().setDrawingEngine(payload.drawingEngine);
         await Promise.all([useCanvasStore.persist.rehydrate(), useAssetStore.persist.rehydrate(), useConfigStore.persist.rehydrate()]);
         // Zustand 在目标 scope 没有快照时会保留旧内存，必须显式恢复该 scope 的空状态。
         if (!persistedCanvas) useCanvasStore.setState({ projects: [] });