Improve Mean/Otsu/Hog/Integral/Interleave/Laplace function descriptions in SimdLib.hpp

[ermig1979]

Summary

Align C++ wrapper Doxygen descriptions in SimdLib.hpp with the improved C API wording in SimdLib.h for Mean, Otsu, HOG, Int16ToGray, Integral, Interleave, and Laplace helpers, and record the updates in release 7.2.165 notes.

Improved functions

• Simd::Mean, Simd::OtsuThreshold
• Simd::HogDirectionHistograms, Simd::HogExtractFeatures
• Simd::Int16ToGray
• Simd::Integral (sum / sum+sqsum / sum+sqsum+tilted overloads)
• Simd::InterleaveUv, Simd::InterleaveBgr, Simd::InterleaveBgra
• Simd::Laplace, Simd::LaplaceAbs, Simd::LaplaceAbsSum

Notable doc fixes

• Documented Mean and OtsuThreshold formulas over 256-bin histograms.
• Clarified HogDirectionHistograms gradient, bilinear cell accumulation, and output layout.
• Clarified HogExtractFeatures 31-feature layout and deprecation status.
• Documented Int16ToGray saturation via RestrictRange.
• Clarified Integral output sizes (width+1/height+1), zero first row/column, and sum/sqsum formulas.
• Added per-pixel Interleave* packing formulas.
• Documented Laplace border replication and that LaplaceAbsSum zero-initializes the sum.

Files

• src/Simd/SimdLib.hpp — documentation only
• docs/2026.html — release 7.2.165 Documentation/Improving entries

No test suite run (documentation-only change, as requested).