`qbzd art` prints the now-playing track's artwork_url (already carried on
GET /api/now-playing — an unauthenticated Qobuz CDN URL); `qbzd art --save
PATH` downloads it (notification icons, terminal viewers). A pure-ish client
verb: no new route (reads the shipped now-playing). A daemon-served
GET /api/artwork/current (302) is deferred until a daemon-only client needs it.
Verified: cargo test -p qbzd --bin qbzd -> 269 passed, 0 failed.
cc