Added auth mode status to health check endpoint.

- Introduced auth_mode in health check response
- Updated App.tsx to handle guest mode logic

lightrag_webui/src/api/lightrag.ts

@@ -44,6 +44,7 @@ export type LightragStatus = {
   update_status?: Record<string, any>
   core_version?: string
   api_version?: string
+  auth_mode?: 'enabled' | 'disabled'
 }
 
 export type LightragDocumentsScanProgress = {