gRPC Compression

Message-level compression in gRPC (gzip, snappy, zstd) negotiated via grpc-accept-encoding and grpc-encoding headers, reducing bandwidth for large payloads. Each message can be compressed independently, and the client advertises supported algorithms in the request. Compression is most effective for text-heavy or repetitive payloads; protobuf's binary format is already compact, so gains on small messages are minimal. Per-message compression headers allow mixed compressed and uncompressed streams.