test(internode): pin msgpack compat send sites
Add a checked test manifest for internode dual-encoded request and response payloads so node.proto _bin fields must be explicitly classified as msgpack-only eligible or always dual-write.
The manifest also pins the current JSON encoder call sites for request and response send paths, making future send-site drift visible before rollout.
Co-authored-by: heihutu <[email protected]>