Add API client code and exception(s)

source/Firecrawl/FirecrawlException.cs

@@ -0,0 +1,67 @@
+using System;
+using System.Net;
+
+namespace Firecrawl
+{
+	/// <summary>
+	/// 
+	/// </summary>
+	public class FirecrawlException :
+		Exception
+	{
+		/// <summary>
+		/// 
+		/// </summary>
+		public HttpStatusCode? StatusCode { get; private init; }
+
+		/// <summary>
+		/// 
+		/// </summary>
+		public FirecrawlException() :
+				this(
+					default)
+		{ }
+
+		/// <summary>
+		/// 
+		/// </summary>
+		/// <param name="statusCode"></param>
+		public FirecrawlException(
+			HttpStatusCode statusCode) :
+				this(
+					statusCode,
+					default)
+		{ }
+
+		/// <summary>
+		/// 
+		/// </summary>
+		/// <param name="statusCode"></param>
+		/// <param name="message"></param>
+		public FirecrawlException(
+			HttpStatusCode statusCode,
+			string message) :
+				this(
+					statusCode,
+					message,
+					default)
+		{ }
+
+		/// <summary>
+		/// 
+		/// </summary>
+		/// <param name="statusCode"></param>
+		/// <param name="message"></param>
+		/// <param name="innerException"></param>
+		public FirecrawlException(
+			HttpStatusCode statusCode,
+			string message,
+			Exception innerException) :
+				base(
+					message,
+					innerException)
+		{
+			StatusCode = statusCode;
+		}
+	}
+}