- Convert WsReadInfo from mutable struct to class (prevents silent copy bugs)
- Add handshake timeout enforcement via CancellationToken in WsUpgrade
- Use buffered reading (512 bytes) in ReadHttpRequestAsync instead of byte-at-a-time
- Add IAsyncDisposable to WsConnection for proper async cleanup
- Simplify redundant mask bit check in WsReadInfo
- Remove unused WsGuid and CompressLastBlock dead code from WsConstants
- Document single-reader assumption on WsConnection read-side state
