Browser Utilities

Dependency-free browser helpers shared by LocalMode UI components: formatBytes, validateFile, readFileAsDataUrl, downloadBlob, the useObjectUrl hook, and the image/canvas ops getImageDimensions, applyMaskToImage, imageResultToDataUrl, downloadDataUrl plus the pure compositeMaskAlpha kernel. No AI, no @localmode dependency — so the components that use them install and compile in any React app.