feat(library): genre sliders, artist links, and navigation utils

- music landing: diverse per-genre album sliders (online counts /
  offline wide-probe fallback) and home-screen library shortcuts
- add ArtistLinks component and shared navigation/genreDiversity utils
- player/playback-mode refinements across Rust and frontend

src-tauri/src/commands/player/mod.rs

@@ -224,6 +224,10 @@ pub struct PlayTracksRequest {
     pub start_index: usize,
     pub shuffle: bool,
     pub context: PlayTracksContext,
+    /// Position (seconds) to resume the starting track from. Used when taking
+    /// over playback from a remote session so we don't restart from 0.
+    #[serde(default)]
+    pub start_position: Option<f64>,
 }
 
 /// Context information for track playback
@@ -1531,7 +1535,7 @@ pub async fn player_play_tracks(
 
     // Play queue
     let controller = player.0.lock().await;
-    controller.play_queue(media_items, request.start_index)
+    controller.play_queue_from(media_items, request.start_index, request.start_position)
         .map_err(|e| e.to_string())?;
 
     // Set queue context