fix(web): use fatal error class for auth-related chat errors

Co-authored-by: Cursor <cursoragent@cursor.com>

web/src/App.tsx

@@ -2062,7 +2062,7 @@ export default function App() {
       return {
         userMessage: detail || '当前账号不是该文档任务的职责人，无法执行',
         code,
-        class: 'auth',
+        class: 'fatal',
         actions: ['retry'],
       };
     }
@@ -2070,7 +2070,7 @@ export default function App() {
       return {
         userMessage: '登录已失效，请重新登录后再试',
         code: 'ERR_UNAUTHENTICATED',
-        class: 'auth',
+        class: 'fatal',
         actions: ['retry'],
       };
     }
@@ -2079,14 +2079,14 @@ export default function App() {
         return {
           userMessage: detail || '无权访问该项目，请确认登录账号与项目成员身份',
           code: code || 'ERR_FORBIDDEN',
-          class: 'auth',
+          class: 'fatal',
           actions: ['retry'],
         };
       }
       return {
         userMessage: detail || '无权执行该操作，请确认账号权限与工作流阶段',
         code: code || 'ERR_FORBIDDEN',
-        class: 'auth',
+        class: 'fatal',
         actions: ['retry'],
       };
     }