Extracts the two Qobuz-driven sidebar sections from /artist/page data
the artist controller already receives and wires them into the
NetworkSidebar.
Controller (`crates/qbz-slint/src/artist.rs`):
- Labels collected during the existing release-bucketing loop,
matching Tauri's extractLabelsFromPageReleases: only the "album"
release group, only releases attributed to this artist, dedupe by
label id, sorted by name. Each label exposes {id, name}.
- Similar artists pulled from page.similar_artists.items as
{id, name}. No artwork on the sidebar rows (Tauri only renders a
User icon + name there).
- ArtistData / ArtistState gained `labels` and `similar_artists`;
reset_artist clears them on artist change.
Slint (`ui/state.slint`, `ui/artist/ArtistPageView.slint`):
- New LabelEntry and SimilarEntry structs alongside ArtistState.
- New SidebarLink local component — small leading icon (12px) +
elided name, surface-elevated hover, mirrors Tauri's
`.sidebar-artist-link`. Used by Labels (Disc), Similar (User),
and the upcoming Relationships rows.
- Labels section: title + items or "No label info" placeholder.
- Similar Artists section: title + items, with "Loading…" while
the artist page itself is loading and "No similar artists found"
once loaded with an empty list.
main.rs:
- on_artist_clicked now navigates: records nav history and calls
navigate_artist, same flow as the top-level on_open_artist. The
target view exists in Slint already (unlike LabelReleases /
ArtistsByLocation / MusicianPage, which stay logged-only).
cc