fix: startup speed, image retry, shuffle random start, genres, search badge, playlist refresh

- Remove await on fetchRomajiIndex() at startup so navigation is not blocked
  by the romaji index network call (was the main cause of 30s Android startup)
- Add window._imgRetry() with 3 retries (1.5s/3s/4.5s backoff) for all card/
  song/cover images that fail to load; falls back to emoji only after exhausting retries
- playQueue with HAS_BRIDGE + shuffle: pick a random startIdx so album/playlist
  playback starts at a random track, not always index 0
- Reduce mobile genre grid limit from 12 to 6
- Fix "Global Suche" badge text: was "iTunes Store + Local", now "iTunes Store"
- deleteSong: always refresh loadPlaylists() unconditionally (not just when
  page is active) with a 3s delay so song counts are current when navigating back

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.js

@@ -94,7 +94,7 @@ async function startApp() {
     if (bnav) bnav.style.display = '';
     absLoadSettingsLibraries();
   }
-  if (S.cfg.showRomaji) await fetchRomajiIndex().catch(() => {});
+  if (S.cfg.showRomaji) fetchRomajiIndex().catch(() => {}); // fire-and-forget — don't block navigation
   if(_navLoad() && S._navCursor >= 0 && S._navStack[S._navCursor]) {
     const last = S._navStack[S._navCursor];
     S._navJumping = true;