YouTube channel descriptions pad their contact/link blocks with runs of blank
lines, which the About popover renders verbatim (whitespace-pre-wrap) — wasted
space and storage, and noise in the search_vector. Add normalize_description()
and apply it at both channel store sites (full details + initial import) so the
DB holds the clean text. New channels are clean immediately; existing rows heal
on their next metadata re-sync. Unit-tested in test_utils.