Fix a typo in progress notification method name

It shoud be `notifications/progress` not `notification/progress` (not singular).

This matches the latest spec.

https://modelcontextprotocol.io/specification/2025-06-18/basic/utilities/progress

client/src/lib/hooks/useConnection.ts

@@ -167,7 +167,7 @@ export function useConnection({
           // Add progress notification to `Server Notification` window in the UI
           if (onNotification) {
             onNotification({
-              method: "notification/progress",
+              method: "notifications/progress",
               params,
             });
           }