* print, ui: a printer is shown by its name, not its CUPS queue name
CUPS queue names can't hold dots or spaces, so macOS adds the printer at
192.0.2.15 as the queue `_192_0_2_15`, and the Print dialog showed that
underscored name. The name the user knows is the queue's description
(CUPS `printer-info`).
craft-print now lists queues with `lpstat -l -p -d` (same lines, plus
each queue's indented details) and keeps the first `Description:` as
`Printer::description`, capped at 256 characters. Windows names are
already human, so they leave it empty.
craft-ui's `Printer` gains `label`; the dialog shows it, or the name when
it's empty, and `shown_names` adds the queue name in brackets when two
printers would show the same text. Selection and jobs still use `name`.
Both structs gain a field, so apps that build them by hand add it
(`..Default::default()` works for craft-ui's) when they update the pin.
* print, ui: an empty first description stays first, and shown names never collide
parse_lpstat tracks whether a queue has had its Description line, so an
empty first one isn't replaced by a later one. shown_names checks the
final texts: printers whose bracketed text another label already reads
show their queue names instead.
