Models: add macConfigPath to McpClient for macOS config path selection (fixes CS1061 in editor window).

UnityMcpBridge/Editor/Models/McpClient.cs

@@ -5,6 +5,7 @@ namespace MCPForUnity.Editor.Models
         public string name;
         public string windowsConfigPath;
         public string linuxConfigPath;
+        public string macConfigPath; // optional macOS-specific config path
         public McpTypes mcpType;
         public string configStatus;
         public McpStatus status = McpStatus.NotConfigured;