compose-capture-to-share-image

Render a composable off-screen into an ImageBitmap so a button can save or share it as a picture — a capture primitive ported into common code rather than pulled in as a platform-only dependency, a max-width ceiling standing in for a fixed output size, artwork that has to already be resolved before the button is even reachable, and an Android MediaStore save gated behind a permission that the same feature's Desktop…