Show reset/copy errors in identity dialog

front/src/App.tsx

@@ -158,11 +158,13 @@ function App() {
   const [identityDialogOpen, setIdentityDialogOpen] = useState(false);
   const [identityToken, setIdentityToken] = useState('');
   const [identityVisible, setIdentityVisible] = useState(false);
+  const [identityError, setIdentityError] = useState('');
 
   useEffect(() => {
     const handler = () => {
       setIdentityToken(localStorage.getItem('identity_token') || '');
       setIdentityVisible(false);
+      setIdentityError('');
       setIdentityDialogOpen(true);
     };
     window.addEventListener('identity_invalid', handler as EventListener);
@@ -208,10 +210,17 @@ function App() {
                                 disabled={!identityVisible}
                                 onClick={() => {
                                   if (!identityVisible || !identityToken) return;
-                                  navigator.clipboard.writeText(identityToken).catch(() => {});
+                                  navigator.clipboard.writeText(identityToken).catch(() => {
+                                    setIdentityError('复制失败，请手动选择内容');
+                                  });
                                 }}
                               />
                             </div>
+                            {identityError && (
+                              <Text block style={{ marginTop: tokens.spacingVerticalXS, color: tokens.colorPaletteRedForeground1 }}>
+                                {identityError}
+                              </Text>
+                            )}
                           </div>
                         </DialogContent>
                         <DialogActions>
@@ -227,9 +236,11 @@ function App() {
                               try {
                                 const token = await reset_identity_token();
                                 setIdentityToken(token);
+                                setIdentityError('');
                                 setIdentityDialogOpen(false);
                               } catch (err) {
                                 console.error('Failed to reset identity token:', err);
+                                setIdentityError('重置失败，请稍后重试');
                               }
                             }}
                           >