feat(core): add allowGuestDemoWorkspace flag to force login (#12779)

https://github.com/user-attachments/assets/41a659c9-6def-4492-be8e-5910eb148d6f

This PR enforces login‑first access (#8716) by disabling or enabling the
guest demo workspace via Admin Server Client Page and redirecting
unauthenticated users straight to `/sign‑in`.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added a configuration option to control whether guest users can create
demo workspaces.
* Updated server and client interfaces, GraphQL schema, and queries to
support the new guest demo workspace flag.

* **Bug Fixes**
* Improved sign-out behavior to redirect users appropriately based on
guest demo workspace permissions.
* Enhanced navigation flow to handle guest demo workspace access and
user authentication state.

* **Tests**
* Added tests to verify sign-out logic when guest demo workspaces are
enabled or disabled.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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Co-authored-by: liuyi <forehalo@gmail.com>
Co-authored-by: fengmk2 <fengmk2@gmail.com>

packages/frontend/core/src/mobile/components/workspace-selector/menu.tsx

@@ -228,7 +228,8 @@ const CloudWorkSpaceList = ({
 
   const handleSignOut = useAsyncCallback(async () => {
     await authService.signOut();
-  }, [authService]);
+    navigateHelper.jumpToSignIn();
+  }, [authService, navigateHelper]);
 
   const handleSignIn = useAsyncCallback(async () => {
     globalDialogService.open('sign-in', {