libzmq backend for OMQ using FFI

Drop-in Rust backend for OMQ. Same socket API (REQ/REP, PUB/SUB, PUSH/PULL, DEALER/ROUTER, and all draft types), but networking runs on a Tokio runtime inside a native extension compiled via rb_sys. Fully interoperable with the default Ruby engine.

Command-line tool for sending and receiving ZeroMQ messages on any socket type (REQ/REP, PUB/SUB, PUSH/PULL, DEALER/ROUTER, and all draft types). Supports Ruby eval (-e/-E), script handlers (-r), pipe virtual socket with Ractor parallelism, multiple formats (ASCII, JSON Lines, msgpack, Marshal), Zstd/LZ4 compression, and CURVE encryption. Like nngcat from libnng, but with Ruby superpowers.

Adds lz4+tcp:// endpoint support to OMQ with per-part LZ4 block-format compression, bounded decompression, in-band dictionary shipping, and automatic dictionary training.

Experimental Quality of Service plugin for the OMQ pure-Ruby ZeroMQ library. Adds per-hop delivery guarantees: QoS 1 (at-least-once), QoS 2 (exactly-once with peer pinning and dedup), and QoS 3 (exactly-once plus application-level COMP/NACK), using ACK/NACK command frames and xxHash message identification.

Bridge OMQ sockets into Ruby Ractors for true parallel processing

Adds ws:// and wss:// transports to OMQ, implementing ZeroMQ RFC 45 (ZWS 2.0). Built on async-websocket. Registers both schemes on require; no OMQ core changes required beyond the .connection_class hook (omq >= 0.27).

Experimental zstd+tcp:// endpoint support for OMQ with per-frame Zstd compression, bounded decompression, in-band dictionary shipping, and sender-side dictionary training.