Phase 4a of the Search/Artists unification. The app had two artist-
detail implementations: the standalone page Library navigates to via
navigateToArtistDetail (its own route, deep-link support, highlights
Library in the sidebar), and an inline state inside the Artists page
reached via selectArtistForDetail. They rendered similar content but
were separate code paths and kept drifting apart (PR #356 just had
to fix source propagation in both).
Every external caller of selectArtistForDetail (9 sites across
api-monitor.js, discover.js, downloads.js, search.js) now calls
navigateToArtistDetail(id, name, source) directly. Removed ~63 lines
of the navigate-then-setTimeout-then-select dance. Source context
(Spotify/iTunes/Deezer/etc.) carries cleanly through via the new
third argument.
Artists sidebar entry, its inline search, and selectArtistForDetail
all still work — they just have no external callers. Phase 4b will
retire the sidebar entry and artists.js.
