v3 library: artist pages — in-your-library view, similar-in-library, links-only web links (#731)

* v3 library: artist pages — in-your-library view, similar-in-library, links-only web

The greenlit artist-pages feature. Every page renders from LOCAL data;
an optional, opt-in external-links strip is the only network surface.

Server:
- artist_enrichment table (mb_artist_id PK, url_rels JSON, genres JSON,
  fetched_at) — never purged; one row per matched MusicBrainz artist.
- GET /api/artist/{name}/page — all-local: canonical name (+ raw alias
  variants), song/album/mastered counts, album list, similar-in-library
  (top artists by shared genre, self excluded, empty is fine), and the
  artist's MB id when any matched/manual song carries one. THE DENOMINATOR
  LAW: "N mastered" counts songs you OWN (best_accuracy >= 0.9 across the
  artist's library songs), never a global discography — a stored score for
  a song no longer in the library does not count.
- GET /api/artist/{name}/links — lazy, cached-forever: returns the cached
  row, else (external links enabled + network + a known MB artist id) ONE
  throttled artist lookup (inc=url-rels+genres+tags), whitelisted into
  {official, tour, video, social[], wikipedia}. Every URL passes the same
  http(s) scheme gate as art redirects, so a hostile javascript:/data:/file:
  can never reach an href. POST .../links/refresh re-fetches. Offline /
  no-mbid / links-disabled → empty, no error. Both routes demo-blocked.
- Settings keys artist_pages_enabled (default ON — local-only) and
  artist_external_links (default OFF — opt-in per the dev-chat thread).

Frontend (static/v3/songs.js): an in-place sub-render mirroring openAlbum()
with a "← Song Library" back + scroll restore. 2x2 album-art mosaic header
(borrows the playlist-cover renderer), canonical name + "also shown as"
variants + a Matched·MusicBrainz pill when known; stats strip that omits
the mastered segment at zero (invitational, never "0 mastered"); Play all /
Shuffle (playQueue) + Save as smart playlist (collections rule {artist});
album rail → openAlbum; song list via the artist filter + wireCards;
"Similar in your library" chips → open that artist; and the external-links
row under an "On the web · opens your browser" divider, each link
target=_blank rel=noopener noreferrer with its domain shown — rendered only
when external links are on AND links exist. Empty modules hide.

Entry points: card ⋮ "Go to artist", the grid card artist line, and a
"View artist page" link in the Details drawer — all via
window.__fbOpenArtistPage.

Tests: tests/test_artist_page.py — page counts/albums/alias folding, the
denominator law (owned-only, best-across-arrangements), similar ranking +
empty, mb-id only from matched rows, links whitelist + scheme gate (a
javascript: and an ftp:// URL both rejected), disabled-by-default no
network, cache-no-second-fetch, refresh, demo block. 21 pass (35 with
artist_alias). node --check clean; tailwind rebuilt.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Nm7tHs1Yvjjtnnu4nzJgdN

* fix(v3 artist pages): unfiltered album view + select-mode row guard on artist page

Artist-page album click no longer applies the global library filters: openAlbum
gains an ignoreFilters option that builds the /api/library request scoped only to
artist+album (no drawer/genre/tuning/search params), so the album view and
Play-album match the artist page's full-shelf counts. The normal albums-view
click path is unchanged (ignoreFilters defaults off).

Select-mode row clicks on the artist page now toggle selection instead of playing.
Extracted the grid/tree capture-phase select guard into a shared bindSelectGuard()
and attach it to the persistent artist-page host too. Each host is bound once at
shell build; innerHTML re-renders reuse the same element, so there is no
double-binding.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: byrongamatos <xasiklas@gmail.com>

static/v3/index.html

@@ -785,6 +785,19 @@
                             <span id="enrich-status" class="text-xs text-gray-500"></span>
                         </div>
                     </div>
+                    <!-- Artist pages (PR-B — wired by static/v3/match-review.js). Sits
+                         beside the Metadata matching card; the Settings→Library tab
+                         regroup is a separate PR. -->
+                    <div class="fb-srow fb-srow-stack">
+                        <div class="fb-srow-main">
+                            <div class="fb-srow-title">Artist pages</div>
+                            <div class="fb-srow-desc">A page for every artist in your library — their songs, albums and your practice progress, built entirely from your local collection. External links (official site, tour dates, videos, social) come from one MusicBrainz lookup per matched artist and always open in your browser — nothing plays in-app, and they stay off until you opt in.</div>
+                        </div>
+                        <div class="grid grid-cols-2 gap-2 mb-1 text-xs text-gray-400 fb-srow-wide">
+                            <label class="flex items-center gap-2"><input type="checkbox" id="artist-pages-enabled" checked class="rounded border-gray-600 bg-dark-700 text-accent"> Artist pages</label>
+                            <label class="flex items-center gap-2"><input type="checkbox" id="artist-external-links" class="rounded border-gray-600 bg-dark-700 text-accent"> Show external links (opens your browser)</label>
+                        </div>
+                    </div>
                     <!-- Backup -->
                     <div class="fb-srow fb-srow-stack">
                         <div class="fb-srow-main">