Best-effort MIME type from a filename's extension — mainly image kinds
(png/jpg/jpeg/gif/webp/avif/svg/bmp/ico). Returns undefined when the
extension isn't recognized (the caller falls back to application/octet-stream).
Used by MountFs.readBlob / MountFs.readObjectUrl; exported so an
app can label a Blob it builds itself.
Best-effort MIME type from a filename's extension — mainly image kinds (png/jpg/jpeg/gif/webp/avif/svg/bmp/ico). Returns
undefinedwhen the extension isn't recognized (the caller falls back toapplication/octet-stream). Used by MountFs.readBlob / MountFs.readObjectUrl; exported so an app can label a Blob it builds itself.