The azimuthal-integration solid-angle correction used cos^3(2*theta), where
2*theta is the true scattering angle (from LabCoord, including detector tilt).
The solid angle of a flat pixel actually depends on the incidence angle to the
detector normal, cos(alpha) = det_distance / |detector-frame position|, which is
invariant under detector tilt (rot1/rot2/rot3). Only for an untilted detector do
the two agree. Switch CalcAzIntSolidAngleCorr(x,y) to the tilt-invariant form,
matching PyFAI solidAngleArray and MAX IV azint. Drop the q-only overload (it can
only ever be the untilted approximation and was used only in tests) and move its
test onto the (x,y) form; add a tilt-invariance test.
XtalOptimizer's residual reconstructed each spot's lab position from rot1/rot2
only, hardcoding rot3 = 0, while the rest of the pipeline (and its own spot
selection) used the full PONI rotation. An imported non-zero rot3 was therefore
silently dropped during refinement. Bake rot3 into the residual as a fixed
Rz(-rot3) so refinement stays consistent (no-op when rot3 == 0).
Polarization and azimuthal binning already honoured rot3 via the full PONI
rotation (Phi_rad), validated against PyFAI chi() by the existing rot3 phi tests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>