Improve description of structure Simd::ImageMatcher

[ermig1979]

Summary

Improved Doxygen descriptions of structure Simd::ImageMatcher in src/Simd/SimdImageMatcher.hpp from real usage in src/Use/UseImageMatcher.cpp (report all similar pairs) and src/Test/TestImageMatcher.cpp (filter unique images). Added the change to release 7.2.166 notes in docs/2026.html.

The comments now describe:

• Reduced-image matching (16x16 / 32x32 / 64x64) with a 4x4 fast hash pre-filter and normalized RMS difference
• Typical Init → Create → Find → Add flow, with Tag as a source index (size_t)
• Two usage patterns: filter unique images (Add only when Find is false) and report all similar pairs (always Add, read Result::hash->tag and difference * 100)
• Init matcher selection from number, threshold and normalized
• Create converting non-Gray8 to Gray8 and resizing with SimdResizeMethodArea
• Correct Empty() meaning (true before Init) and the Hash64x64 size (was wrongly documented as 32x32)
• Skip() excluding a stored hash from later Find without removing it

No executable code was changed. The test suite was not run, as requested.

Files

• src/Simd/SimdImageMatcher.hpp
• docs/2026.html (release 7.2.166)

Updated ImageMatcher comments
Release 7.2.166 notes

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