feat: disambiguate same-name artists by Deezer fan count + show fans

Deezer's artist search doesn't rank by popularity, so a name collision (5 artists named
"Joji") returned a niche one first (62 fans) instead of the real Joji (559k) — the artist
page then loaded the wrong discography and owned songs didn't show as downloaded.

- api.js: _dzArtist carries fanCount (nb_fan); artist search sorts by fanCount desc.
- search.js: artist cards show the fan count as subtitle; fan count passed to the artist page.
- detail.js: pick the most-popular name match (not the first); for local Navidrome artists
  with a real collision (>=2 same-name candidates), tie-break by SONG OVERLAP — prefer the
  Deezer candidate whose top tracks actually overlap the library (each artist has different
  songs, so this nails the right person). Costs a few calls only on a collision.
- Artist hero shows "<n> Fans" (immediately for global-search artists, after match for local).
- Android: DzArtist.nb_fan + /search/artist sorted by nb_fan so the right artist is first.
- Also: web global-search "unavailable" message now says Deezer, not Apple. SW ns-v52.

Verified live against Deezer: both fan-sort and overlap select the real Joji (id 5078097).

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

src/utils.js

@@ -45,6 +45,15 @@ export function formatDur(s) {
   return `${m}:${sec.toString().padStart(2,'0')}`;
 }
 
+// Compact count for fan numbers etc.: 559534 → "559,5 Tsd.", 1200000 → "1,2 Mio."
+export function fmtCount(n) {
+  if (n == null || isNaN(n)) return '';
+  const de = x => x.toFixed(1).replace(/\.0$/, '').replace('.', ',');
+  if (n >= 1e6) return de(n / 1e6) + ' Mio.';
+  if (n >= 1e3) return de(n / 1e3) + ' Tsd.';
+  return String(n);
+}
+
 export function toast(msg) {
   const t = document.createElement('div');
   t.className = 'toast';