v0.1.0

• Send application/grpc and use shared metadata decoding, including unpadded binary metadata.
• Map invalid HTTP responses to grpc-ruby errors, preserving the native ResponseError and its buffered response as the cause.
• Support deferred unary operations with execution, cancellation, deadline, status, and response metadata access.
• Support Ruby authentication callbacks at stub construction and per call, evaluated on each execution with the service's JWT audience and merged into request metadata.
• Support custom trust roots and mutual TLS through IO::Endpoint::TLS::Configuration. Reject opaque native credentials, conflicting target schemes, and authentication callbacks on plaintext channels.
• Map grpc-ruby's TLS constructor arguments with Compatible::ChannelCredentials.new(root_certificates, private_key, certificate_chain), returning an IO::Endpoint::TLS::Configuration with custom roots, client certificate chains, and peer verification enabled.
• Add ClientStub.for(service) and the optional GapicServiceStub adapter for generated services and GAPIC clients.
• Map transport failures to grpc-ruby errors, preserving the original exception as the cause. Connection, DNS, TLS, and HTTP/2 connection failures become GRPC::Unavailable, and HTTP/2 stream resets use gRPC's HTTP/2 status mapping.
• Share connections between stubs for the same target and TLS configuration on each thread, like grpc-core's global subchannel pool. Closing a stub leaves shared clients open; use SharedChannel.close to close the current thread's shared clients, or set grpc.use_local_subchannel_pool for a stub-owned connection pool.