feat(artist pin): pin by Deezer link/ID when search can't surface the artist

Deezer's /search/artist is a ranked, incomplete fuzzy match — low-profile
same-name artists (e.g. Nana id 80239872) never appear in results. Add a
"paste Deezer link or ID" field to the pin picker that looks the artist up
directly via /artist/{id} (new deezerLookupArtist) and pins it. Same reliable
route as the importer direct link vs yt-dlp search.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/api.js

@@ -425,6 +425,20 @@ export async function deezerLookupArtistAlbums(artistId, limit=100, artistName='
   } catch { return []; }
 }
 
+// Direct artist lookup by Deezer id — the reliable route when /search/artist doesn't surface a
+// low-profile same-name artist (Deezer search is a ranked, incomplete fuzzy match; e.g. the browser
+// finds Nana id 80239872 but the search API never returns it). Used by the artist-pin "paste link"
+// path. Returns the full _dzArtist shape (or null on miss / bad id).
+export async function deezerLookupArtist(artistId) {
+  try {
+    const r = await fetch(`${_deezerBase()}/artist/${artistId}`);
+    if (!r.ok) return null;
+    const a = await r.json();
+    if (!a || a.error || !a.id) return null;
+    return _dzArtist(a);
+  } catch { return null; }
+}
+
 // Deezer artist photo (for the hero on non-local artist pages). iTunes artist entities had none.
 export async function deezerArtistImage(artistId) {
   try {