Replace the stubbed chat API with a real WebSocket hook that
connects to /ws/chat and supports DM creation, messaging,
session join/leave, and history retrieval. Keep REST stub
functions for backward compatibility with existing pages
that require listChatSessions/getChatSessionById imports.
The function performed client-side filtering on top of listOrders
but was never called by any page. listPlayersByShop is kept as-is
since the backend has no dedicated shop players endpoint.
Rewrite store/notifications.ts to fetch via listNotifications
API and remove local generateId-based notification creation.
The store now acts as a simple cache with fetch/invalidate methods.
Header unread count reads from this API-backed cache.
zetaloop