The previous BigInt-safe JSON.stringify converted bigint to string but
did not handle protobuf well-known types (Timestamp, Duration, etc.)
which require canonical JSON encoding (e.g. RFC 3339 for Timestamp).

When the handler returns a protobuf message ($typeName detected) and
the method descriptor carries the output schema, serializeResult now
uses @bufbuild/protobuf's toJson() for proper encoding. Falls back to
BigInt-safe stringify for plain objects or when protobuf is unavailable.

Made-with: Cursor