新增 全局错误toast提示；

src/App.tsx

@@ -7,6 +7,7 @@ import { ImageCanvas } from './components/ImageCanvas';
 import { HistoryPanel } from './components/HistoryPanel';
 import { useKeyboardShortcuts } from './hooks/useKeyboardShortcuts';
 import { useAppStore } from './store/useAppStore';
+import { ToastProvider } from './components/ToastContext';
 
 const queryClient = new QueryClient({
   defaultOptions: {
@@ -59,7 +60,9 @@ function AppContent() {
 function App() {
   return (
     <QueryClientProvider client={queryClient}>
-      <AppContent />
+      <ToastProvider>
+        <AppContent />
+      </ToastProvider>
     </QueryClientProvider>
   );
 }