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/ProtocolConstants.cs

@@ -0,0 +1,20 @@
+namespace HSchool.Protocol;
+
+/// <summary>Wire-format constants shared by the server and the browser client.</summary>
+public static class ProtocolConstants
+{
+    /// <summary>Bumped on every breaking change to the binary layout.</summary>
+    public const byte Version = 1;
+
+    /// <summary>Upper bound for a single WebSocket frame accepted by the server.</summary>
+    public const int MaxMessageSize = 64 * 1024;
+
+    /// <summary>Bytes of a single entity inside a snapshot payload.</summary>
+    public const int EntitySnapshotSize = sizeof(uint) + sizeof(byte) + (sizeof(float) * 3) + sizeof(uint);
+
+    /// <summary>Bytes of the snapshot header: message type + tick + entity count.</summary>
+    public const int SnapshotHeaderSize = sizeof(byte) + sizeof(uint) + sizeof(ushort);
+
+    /// <summary>Maximum UTF-8 byte length of a player name.</summary>
+    public const int MaxPlayerNameBytes = 32;
+}