feat(core): show login modal if not logged in when using ai (#6632)

![CleanShot 2024-04-22 at 09.05.42.gif](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/LakojjjzZNf6ogjOVwKE/61b35d07-5d5a-4df9-859b-17cf7a9c20cf.gif)

packages/frontend/core/src/providers/modal-provider.tsx

@@ -88,6 +88,12 @@ const HistoryTipsModal = lazy(() =>
   }))
 );
 
+const AiLoginRequiredModal = lazy(() =>
+  import('../components/affine/auth/ai-login-required').then(module => ({
+    default: module.AiLoginRequiredModal,
+  }))
+);
+
 export const Setting = () => {
   const [{ open, workspaceMetadata, activeTab }, setOpenSettingModalAtom] =
     useAtom(openSettingModalAtom);
@@ -206,6 +212,7 @@ export function CurrentWorkspaceModals() {
       {currentWorkspace?.flavour === WorkspaceFlavour.AFFINE_CLOUD && (
         <CloudQuotaModal />
       )}
+      <AiLoginRequiredModal />
     </>
   );
 }