Any other live use of the packed register keeps throwing, as on main, instead of
reading SampleId << 8 | Layer << 16 with the other bits zero. The field range
check no longer underflows for an extract that starts past a field's end.
Adds the pixel_ancillary recompiler test.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Michon