feat(composer): Browse by Composer page (issue #465) (#487)

* feat(composer): Browse by Composer page (issue #465)

New library section listing every artist credited as composer on at
least one track, with a detail page showing all works they're credited
on in that role. Targeted at classical-music libraries where the
"recording artist" tag carries the orchestra and the "composer" tag
carries Bach / Mozart / Chopin.

Hits Navidrome's native /api/artist?_filters={"role":"composer"} for
the listing and /api/album?_filters={"role_composer_id":"…"} for the
works grid — Subsonic getArtist only follows AlbumArtist relations and
returns 0 albums for composer-only credits, so the native API is the
only path that works. Requires Navidrome 0.55+ (uses
library_artist.stats role aggregation); on older / pure-Subsonic
servers the page shows a one-line capability banner.

- Two new Tauri commands: nd_list_artists_by_role +
  nd_list_albums_by_artist_role, generic over participant role so
  conductor / lyricist / arranger pages are trivial to add later.
- Composers grid: text-only compact tiles (name + participation count
  pulled from stats[role].albumCount). No avatars — composer libraries
  carry no useful imagery and the listing endpoint exposes no image
  URLs anyway.
- ComposerDetail: hero with Last.fm bio (via getArtistInfo2) plus the
  full work grid, with a graceful fallback when the artist has no
  external info synced.
- Sidebar entry default off (Feather icon) — opt-in for the niche
  classical use case.
- nd_retry backoffs widened from [500] to [300, 800, 1800] — helps
  every nd_* call survive intermittent TLS-handshake-EOF errors that
  some reverse-proxy setups produce when keep-alive pools churn.
- Distinguishes "server can't do this" (HTTP 400/404/422/501) from
  transient errors so the capability banner only fires when the server
  actually rejects the request shape; everything else gets a retry
  button.
- i18n in all 8 supported locales.

* fix(composer): address review feedback on detail page + role queries

- Re-fetch ComposerDetail when music-library scope changes; previously
  the album grid stayed stale until navigation while the list refreshed.
- Thread library_id through nd_list_artists_by_role and
  nd_list_albums_by_artist_role so role queries respect the active
  Navidrome library, matching the Subsonic musicFolderId already piped
  through libraryFilterParams().
- Fix CachedImage cache-key mismatch on ComposerDetail: a Last.fm header
  image was stored under the Subsonic cover-art key, aliasing cache
  entries and risking cross-source pollution.
- Consolidate the two contradictory composer-imagery comments in
  Composers.tsx into a single accurate one (the older one referenced an
  Images toggle that was never implemented).
- Align openLink toast duration with ArtistDetail (1500ms -> 2500ms).

* fix(composer): keep bio across scope changes, add share, degrade gracefully

Three remaining items from the latest review pass on the composer flow.

1. Bio survives a music-library scope change.
   The previous fix added musicLibraryFilterVersion to the load effect,
   but that effect also did setInfo(null) while the getArtistInfo effect
   still depended on [id] alone — so a scope bump on the open page
   wiped the bio without re-fetching it. Move the info reset into the
   bio effect (keyed on id) and out of the load effect: the album grid
   still refreshes on scope change; the Last.fm header image and
   biography survive untouched, since both are library-independent.

2. Composers join the share pipeline as a first-class entity kind.
   Extend EntityShareKind with 'composer' (and isEntityKind), branch
   applySharePastePayload to validate via getArtist (same id pool) and
   navigate to /composer/:id, and wire a Share button into
   ComposerDetail. A pasted composer link now opens the composer view
   instead of the artist view, matching what was copied. i18n added in
   all 8 locales (sharePaste.composerUnavailable, openedComposer;
   composerDetail.shareComposer, unknownComposer).

3. Partial server failure no longer hides the works.
   If getArtist rejects but ndListAlbumsByArtistRole succeeds, the page
   used to show full "not found" despite having data to display. Switch
   the not-found gate to require both empty (`!artist && !albums`) and
   render a degraded header (placeholder name, no Wikipedia / favourite
   / share / Last.fm image) when only metadata is missing.

* fix(composer): right-click share copies a composer link, not an artist link

The context menu opened from a composer card / row uses type='artist'
because every composer-action (radio, favourite, rating, add-to-playlist)
is identical to the artist counterpart — they share an id space and a
backend representation. Sharing was the one exception: the "Share Link"
entry produced a 'psysonic2-' string with k='artist', so a paste opened
/artist/:id even though the user came from /composers.

Add an optional shareKindOverride to openContextMenu (default: undefined,
preserves existing behaviour) and have the artist-typed branch consult
it when calling copyShareLink. Composers.tsx now passes 'composer' on
both right-click sites; nothing else changes downstream because the
override only affects the share kind.

* polish(composer): show Last.fm avatar even without server metadata

Two minor follow-ups from the latest review.

- ComposerDetail: drop the `&& artist` guard on the header-avatar render
  path. info?.largeImageUrl can resolve through getArtistInfo(id) without
  ever needing the SubsonicArtist record, so the previous gate hid a
  perfectly good Last.fm portrait whenever getArtist failed but the
  bio fetch succeeded. Replace artist.name with displayName so the
  alt / aria-label degrade to the localised "Composer" placeholder
  instead of empty strings.
- copyEntityShareLink: doc comment now mentions composer alongside
  track / album / artist.

* fix(composer): derive Last.fm cache key from route id, not from artist record

Follow-up to the previous polish: the avatar render path no longer
requires `artist` to be populated, but the cache-key gate still did. So
when getArtist failed but getArtistInfo returned a Last.fm portrait, the
key fell through to coverKey — which is empty without an artist record,
re-creating the very aliasing bug the earlier Subsonic-vs-Last.fm fix
was meant to close.

Switch the Last.fm branch to the route id (same id namespace as the
SubsonicArtist record), so the key stays stable whenever Last.fm art is
shown, independent of getArtist succeeding.

* docs: CHANGELOG + Contributors entry for composer browsing (PR #487)

src/pages/Settings.tsx

@@ -368,6 +368,7 @@ const CONTRIBUTORS = [
       'Library: "favorites only" filter on Albums, Artists and Advanced Search — toolbar toggle reading star overrides live (PR #466)',
       'Settings: keep current active server when adding a new one — no more auto-switch interrupting playback or library context (PR #475)',
       'Help page: full rewrite with 45 focused entries across 10 themed sections (Getting Started / Playback & Queue / Audio Tools / Library & Discovery / Lyrics / Sharing & Social / Personalization / Power User / Offline & Sync / Integrations & Troubleshooting), in-page live search with case-insensitive substring matching and auto-expand on hits, translated to all 8 locales (PR #485)',
+      'Library: Browse by Composer — native-API role listing for classical libraries, library-scoped queries, composer as a first-class share entity (PR #487)',
     ],
   },
 ] as const;