* Cover a couple of more cases on data track runt packet handling.
* Guard data track header parser against extensions-size integer wraparound.
Widen the extensions-size arithmetic to int so a 0xFFFF wire value no
longer wraps in uint16, and reject any packet whose computed hdrSize
exceeds the buffer before slicing the payload.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>