- BinaryReader.scanLines(): one pass inside the environment locates and
measures a span of lines, decoded exactly like the whole file
- read detects images from the header and PNG chunk headers, scans once,
and decodes only the head it shows; differential test against the
whole-file algorithm
- StreamDecoder: Node's streaming TextDecoder dropped a U+FEFF after a chunk
boundary in shell output and line readers
- fix the harness test to pick its tool result by call id
