fix(studio): 笔记切换页面不刷新 + 侧边栏错误提示友好化

- WorkspaceRoutes 给 StudioNotebookDetailPage 加 key={notebookId}，切换笔记时强制重新挂载
- createSearchSpace 接口失败时解析响应体 detail 字段，直接展示服务端错误信息

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend-web/src/pages/WorkspaceRoutes.tsx

@@ -1,5 +1,5 @@
 import type { CSSProperties, ReactNode } from "react";
-import { Navigate, Route, Routes } from "react-router-dom";
+import { Navigate, Route, Routes, useParams } from "react-router-dom";
 
 import { getStoredAuth } from "@/core/auth";
 
@@ -39,6 +39,11 @@ import AIWritingPage from "@/open-canvas/pages/AIWritingPage";
 import StudioNotebooksPage from "./StudioNotebooksPage";
 import StudioNotebookDetailPage from "./StudioNotebookDetailPage";
 import RoundtablePlanningPage from "@/roundtable-planning/pages/RoundtablePlanningPage";
+
+function NotebookDetailPageWithKey() {
+  const { notebookId } = useParams<{ notebookId: string }>();
+  return <StudioNotebookDetailPage key={notebookId} />;
+}
 import "@/roundtable-planning/styles/roundtable-planning.css";
 
 export function WorkspaceLayout({
@@ -219,7 +224,7 @@ export default function WorkspaceRoutes({
         element={
           <WorkspaceLayout {...layoutProps}>
             <ChatRuntime>
-              <StudioNotebookDetailPage />
+              <NotebookDetailPageWithKey />
             </ChatRuntime>
           </WorkspaceLayout>
         }