Fix PascalCase parameter naming to follow C# conventions

[Copilot]

Parameters in ImageCompare.cs used inconsistent PascalCase naming (Pic1, Pic2, PathActual, etc.) instead of camelCase, violating C# conventions and inconsistent with other parameters in the same file.

Changes

• CalcDiff(SKBitmap Pic1, SKBitmap Pic2, ...) → CalcDiff(SKBitmap pic1, SKBitmap pic2, ...)
• CalcDiffMaskImage(string PathPic1, string PathPic2) → CalcDiffMaskImage(string pathPic1, string pathPic2)
• CalcDiffMaskImage(SKBitmap Pic1, SKBitmap Pic2) → CalcDiffMaskImage(SKBitmap pic1, SKBitmap pic2)
• ImagesAreEqual(string PathActual, string PathExpected) → ImagesAreEqual(string pathActual, string pathExpected)
• ImagesHaveEqualSize(string PathActual, string PathExpected) → ImagesHaveEqualSize(string pathActual, string pathExpected)

XML doc <param> tags updated to match.

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