refactor: remove fake page/view designers, keep dashboard editor

The View 'designer' tab and Page Canvas Editor never produced usable
output. They are removed entirely:

- Drop ObjectViewConfigurator, PageCanvasEditor, PageDesignPage from
  @object-ui/plugin-designer
- Drop DesignDrawer from @object-ui/app-shell; PageView now renders
  pages read-only from metadata
- Drop /design/page route

DashboardEditor + DashboardDesignPage are kept since they are a real,
working editor. /design/dashboard/:dashboardName route is preserved.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: os-zhuang

packages/app-shell/src/console/AppContent.tsx

@@ -53,10 +53,12 @@ const MetadataResourceListPage = lazy(() => import('../views/metadata-admin').th
 const MetadataResourceEditPage = lazy(() => import('../views/metadata-admin').then(m => ({ default: m.MetadataResourceEditPage })));
 const MetadataResourceHistoryPage = lazy(() => import('../views/metadata-admin').then(m => ({ default: m.MetadataResourceHistoryPage })));
 
-// App authoring pages — sourced from @object-ui/plugin-designer so third-party
-// hosts can opt out by not registering these routes.
+// App authoring + dashboard editor pages — sourced from
+// @object-ui/plugin-designer so third-party hosts can opt out by not
+// registering these routes.
 const CreateAppPage = lazy(() => import('@object-ui/plugin-designer').then(m => ({ default: m.CreateAppPage })));
 const EditAppPage = lazy(() => import('@object-ui/plugin-designer').then(m => ({ default: m.EditAppPage })));
+const DashboardDesignPage = lazy(() => import('@object-ui/plugin-designer').then(m => ({ default: m.DashboardDesignPage })));
 
 // Marketplace pages — first-class platform feature; mounted at `system/marketplace`
 // under any active app so admins can browse + install from inside the runtime.
@@ -406,6 +408,7 @@ export function AppContent({ extraRoutes, extraRoutesNoApp }: AppContentProps =
                     landed. Redirect to the new /metadata/:type/... shape. */}
                 <Route path="component/metadata/directory" element={<LegacyMetadataRedirect mode="directory" />} />
                 <Route path="component/metadata/resource/*" element={<LegacyMetadataRedirect mode="resource" />} />
+                <Route path="design/dashboard/:dashboardName" element={<DashboardDesignPage />} />
                 <Route path="search" element={<SearchResultsPage />} />
                 <Route path="create-app" element={<CreateAppPage />} />
                 <Route path="edit-app/:editAppName" element={<EditAppPage />} />

packages/app-shell/src/views/DesignDrawer.tsx

@@ -0,0 +1,61 @@
+/**
+ * Page View Component
+ *
+ * Renders a custom page based on the pageName parameter. Page authoring
+ * happens via the metadata admin (JSON form / preview tabs); no bespoke
+ * canvas editor is offered here.
+ */
+
+import { useParams, useSearchParams } from 'react-router-dom';
+import { SchemaRenderer } from '@object-ui/react';
+import { Empty, EmptyTitle, EmptyDescription } from '@object-ui/components';
+import { FileText } from 'lucide-react';
+import { useObjectTranslation } from '@object-ui/i18n';
+import { MetadataPanel, useMetadataInspector } from './MetadataInspector';
+import { useMetadata } from '../providers/MetadataProvider';
+
+export function PageView() {
+  const { t } = useObjectTranslation();
+  const { pageName } = useParams<{ pageName: string }>();
+  const [searchParams] = useSearchParams();
+  const { showDebug } = useMetadataInspector();
+
+  const { pages } = useMetadata();
+  const page = pages?.find((p: any) => p.name === pageName);
+
+  if (!page) {
+    return (
+      <div className="h-full flex items-center justify-center p-8">
+        <Empty>
+          <div className="mx-auto mb-4 flex h-12 w-12 items-center justify-center rounded-full bg-muted">
+            <FileText className="h-6 w-6 text-muted-foreground" />
+          </div>
+          <EmptyTitle>{t('empty.pageNotFound')}</EmptyTitle>
+          <EmptyDescription>
+            {t('empty.pageNotFoundDescription', { name: pageName })}
+          </EmptyDescription>
+        </Empty>
+      </div>
+    );
+  }
+
+  const params = Object.fromEntries(searchParams.entries());
+
+  return (
+    <div className="flex flex-row h-full w-full overflow-hidden relative">
+      <div className="flex-1 overflow-auto h-full relative">
+        <SchemaRenderer
+          schema={{
+            ...page,
+            type: (page as any).type || 'page',
+            context: { ...(page as any).context, params },
+          }}
+        />
+      </div>
+      <MetadataPanel
+        open={showDebug}
+        sections={[{ title: 'Page Configuration', data: page }]}
+      />
+    </div>
+  );
+}

packages/app-shell/src/views/PageView.tsx

@@ -12,4 +12,3 @@ export { ActionResultDialog, type ResultDialogState } from './ActionResultDialog
 export { MetadataToggle, MetadataPanel } from './MetadataInspector';
 export { ViewConfigPanel } from './ViewConfigPanel';
 export { CreateViewDialog } from './CreateViewDialog';
-export { DesignDrawer } from './DesignDrawer';