Add chat functionality (#1)

* Working chatbot

* Clean

* Working LLM chatbot

---------

Co-authored-by: Myx <info@azaaxin.com>

Bot/Notification/SlashCommandReceivedNotification.cs

@@ -0,0 +1,9 @@
+using Discord.WebSocket;
+using MediatR;
+
+namespace Lunaris2.Notification;
+
+public class SlashCommandReceivedNotification(SocketSlashCommand message) : INotification
+{
+    public SocketSlashCommand Message { get; } = message ?? throw new ArgumentNullException(nameof(message));
+}