feat: add support chat widget demo and state management

- Implemented SupportWidgetDemo component for configuring and mounting the support chat widget.
- Introduced Zustand store for managing support chat state, including message handling and socket connection.
- Created support host bridge for communication between the widget and parent window.
- Added utility functions for JWT token generation and local storage management.
- Enhanced user experience with notifications for new messages and chat status updates.

web/app/support/demo/page.tsx

@@ -1,5 +1,5 @@
-import { KefuWidgetDemo } from "@/components/kefu/widget-demo"
+import { SupportWidgetDemo } from "@/components/support-chat/widget-demo"
 
 export default function Page() {
-  return <KefuWidgetDemo />
+  return <SupportWidgetDemo />
 }