Update .gitignore to exclude TypeScript build info and add dist directory. Expand README with project overview, technology stack, prerequisites, and instructions for running and testing the application.

src/HSchool.Protocol/ProtocolException.cs

@@ -0,0 +1,4 @@
+namespace HSchool.Protocol;
+
+/// <summary>Thrown when a frame is truncated, oversized or otherwise unreadable.</summary>
+public sealed class ProtocolException(string message) : Exception(message);