CHANGELOG: describe reporting ISa at its asymptotic definition (read from the
strong equivalents, relaxed threshold on weak/damaged data) and the frontend
azimuthal-integration Q fields gaining 5-decimal precision.
CPU_DATA_ANALYSIS: update the error-model section - ISa is the counting-
subtracted strong-reflection asymptote (and drives the systematic floor), not
1/b of the whole-range fit.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>