新增私聊相关

Hotfix/Social/Chat/System/ChatChannelSystem.cs

@@ -0,0 +1,28 @@
+using Fantasy;
+
+namespace NB.Chat;
+
+public static class ChatChannelSystem
+{
+    /// <summary>
+    /// 进入频道
+    /// </summary>
+    /// <param name="channel"></param>
+    /// <param name="unit"></param>
+    public static void Enter(this ChatChannel channel, SocialUnit unit)
+    {
+        channel.Units.Add(unit.Id);
+        unit.CurrentChannel = channel.Id;
+    }
+
+    /// <summary>
+    /// 离开频道
+    /// </summary>
+    /// <param name="channel"></param>
+    /// <param name="unit"></param>
+    public static void Exit(this ChatChannel channel, SocialUnit unit)
+    {
+        channel.Units.Remove(unit.Id);
+        unit.CurrentChannel = 0;
+    }
+}