200be77903
Lightroom-style 'Screen' output sharpen (unsharp mask, 3x3 convolution
via Skia ImageFilter.MakeMatrixConvolution, amount 0.5, kernel sums to
1) applied to final pixels before JPEG encode. Camera-capture branch
passes { dpi: 300, sharpen: true }; library-mode export untouched.
Export pixels were already full resolution - sharpen is a new final
GPU pass, no pixel-count change.