feat: v1.30.0 — Discord RPC, offline bulk download, artist images, lazy loading, crossfade fix

- Discord Rich Presence (opt-in) — requested by @Bewenben (#49)
- Bulk offline download for playlists and artist discographies — requested by @Apollosport (#54)
- Offline Library filter tabs: All / Albums / Playlists / Discographies with artist grouping
- Artist images on Artists overview (opt-in, off by default) — reported by @Apollosport (#53)
- Image lazy loading via IntersectionObserver (300px margin) across all pages
- Fix: crossfade no longer triggers on manual track skip — reported by @netherguy4 (#35)
- Fix: playlist offline cache now stored as single entry (not per-album)
- Fix: image cache AbortController no longer blocks IDB writes
- Update toast: experimental auto-update hint + GH download link always visible (Win/Mac)
- Queue tech strip: genre removed
- Facebook theme: contrast, opaque badge/back button, queue tab labels
- "Save discography offline" label (was "Download discography")
- Fix: clearing empty playlists via updatePlaylist.view (Axios empty array workaround)
- starredOverrides propagated to AlbumDetail, Favorites, RandomMix

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

src-tauri/src/audio.rs

@@ -1074,6 +1074,7 @@ pub async fn audio_play(
     duration_hint: f64,
     replay_gain_db: Option<f32>,
     replay_gain_peak: Option<f32>,
+    manual: bool, // true = user-initiated skip → bypass crossfade, start immediately
     app: AppHandle,
     state: State<'_, AudioEngine>,
 ) -> Result<(), String> {
@@ -1137,7 +1138,8 @@ pub async fn audio_play(
 
     let (gain_linear, effective_volume) = compute_gain(replay_gain_db, replay_gain_peak, volume);
 
-    let crossfade_enabled = state.crossfade_enabled.load(Ordering::Relaxed);
+    // Manual skips (user-initiated) bypass crossfade — the track should start immediately.
+    let crossfade_enabled = state.crossfade_enabled.load(Ordering::Relaxed) && !manual;
     let crossfade_secs_val = f32::from_bits(state.crossfade_secs.load(Ordering::Relaxed)).clamp(0.5, 12.0);
 
     // Measure how much audio Track A actually has left right now.