The composer's GIF button drew a filled rounded rect with the letters knocked
out, which reads as a solid square rather than a picker. Invert it: stroked
outline with filled letters, reusing the original glyph paths scaled to centre.
Banners already accept absolute URLs on both ends (server isValidAssetUrl
allows http(s); the profile render branches on banner.startsWith('http')), so
the picker stores the remote URL directly with no upload path. Previews can now
hold either a blob: or an https: URL, so revoking is guarded — calling
revokeObjectURL on a remote URL is a silent no-op that would hide a mistake.