feat: implement multiplayer session state management and add invalid port exception

src/Features/Multiplayer/Contracts/Exceptions/MultiplayerAlreadyConnectedException.cs

@@ -1,6 +1,7 @@
 namespace Game.Features.Multiplayer.Contracts.Exceptions;
 
 /// <summary>
-/// Thrown when trying to host or join while already connected to a session.
+/// Thrown when trying to host or join while connecting or already connected to a session.
 /// </summary>
-public sealed class MultiplayerAlreadyConnectedException() : MultiplayerException("Already connected to a session.");
+public sealed class MultiplayerAlreadyConnectedException()
+    : MultiplayerException("Already connected to or connecting with a session.");

src/Features/Multiplayer/Contracts/Exceptions/MultiplayerInvalidPortException.cs

@@ -0,0 +1,4 @@
+namespace Game.Features.Multiplayer.Contracts.Exceptions;
+
+public sealed class MultiplayerInvalidPortException(int port)
+    : MultiplayerException($"Invalid port {port}. Port must be between 1 and 65535.");

src/Features/Multiplayer/Contracts/Exceptions/MultiplayerInvalidPortException.cs.uid

@@ -0,0 +1 @@
+uid://d3n8p5w2y7c4h