parseUploadedFiles stopped the filename capture at the first "("
([^\n(]+), so an entry like "- photo (1).png (12.3 KB)" failed to
match and the file silently disappeared from the message's file chips.
Browsers produce such names for duplicate downloads, making this a
common real-world shape.
Anchor the size group on the "(<number> <unit>)" pair the backend
emits (uploads_middleware formats sizes as "%.1f KB"/"%.1f MB") and
let the filename match greedily up to it, so parenthesized filenames
parse correctly.