Fix CS0246: add missing using osu.Desktop.IPC; for OsuWebSocketProvider reference

Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/1fd19d7e-9231-44c6-af3c-c266fbf170f3

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot

osu.Desktop/OsuGameDesktop.cs

@@ -6,6 +6,7 @@
 using System.Reflection;
 using System.Runtime.Versioning;
 using Microsoft.Win32;
+using osu.Desktop.IPC;
 using osu.Desktop.MacOS;
 using osu.Desktop.Performance;
 using osu.Desktop.Security;