fn detect_stream_type(first_byte: u8) -> DataStreamTypeExpand description
Determine the data stream type from the first varint on the stream.
MoQT data streams start with a stream type varint:
- 0x04 = Subgroup
- 0x05 = Fetch
The varint itself is not consumed here: the framer is fed the stream from its first byte and the header decoder owns the type field.