Rename all crate directories, package names, binary names, proto
package/module paths, ALPN strings, env var prefixes, config filenames,
mDNS service names, and plugin ABI symbols from quicproquo/qpq to
quicprochat/qpc.
Java SDK: JNI bindings to libquicproquo_ffi with QpqClient class,
Gradle build, and exception hierarchy matching Kotlin SDK.
Ruby SDK: FFI gem wrapping libquicproquo_ffi with Client class,
block-form auto-disconnect, gemspec for RubyGems publishing,
and example script.
