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/routes/player/[id]/+page.svelte

@@ -8,7 +8,7 @@
   import type { MediaItem } from "$lib/api/types";
   import { auth } from "$lib/stores/auth";
   import { library } from "$lib/stores/library";
-  import { queue, currentQueueItem } from "$lib/stores/queue";
+  import { queue, currentQueueItem, isShuffle, repeatMode, hasNext as hasNextStore, hasPrevious as hasPreviousStore } from "$lib/stores/queue";
   import { downloads, type DownloadInfo } from "$lib/stores/downloads";
   import { playbackPosition, playbackDuration, currentMedia as storeCurrentMedia } from "$lib/stores/player";
   import { get } from "svelte/store";
@@ -47,10 +47,12 @@
   const position = $derived($playbackPosition);
   const duration = $derived($playbackDuration);
   let isPlaying = $state(false);
-  let shuffle = $state(false);
-  let repeat = $state<"off" | "all" | "one">("off");
-  let hasNext = $state(false);
-  let hasPrevious = $state(false);
+  // Shuffle/repeat/next/previous are event-driven via the queue store (instant
+  // update on queue_changed), not polled.
+  const shuffle = $derived($isShuffle);
+  const repeat = $derived($repeatMode);
+  const hasNext = $derived($hasNextStore);
+  const hasPrevious = $derived($hasPreviousStore);
   let currentMedia = $state<MediaItem | null>(null);
   let streamUrl = $state<string | null>(null);
   let mediaSourceId = $state<string | null>(null);
@@ -133,14 +135,7 @@
         isVideo = item.type === "Movie" || item.type === "Episode";
         isPlaying = true;
         loading = false;
-        // Sync queue status
-        try {
-          const queueStatus = await commands.playerGetQueue();
-          hasNext = queueStatus.hasNext;
-          hasPrevious = queueStatus.hasPrevious;
-        } catch (e) {
-          // Ignore - queue status will update via polling
-        }
+        // hasNext/hasPrevious come from the event-driven queue store.
         // Fetch next episode for video skip button
         if (isVideo) {
           fetchNextEpisode(item);
@@ -446,13 +441,7 @@
         isPlaying = status.state.kind === "playing";
         // Note: position/duration are now derived from player store (updated by events)
       }
-      shuffle = status.shuffle;
-      repeat = status.repeat;
-
-      // Update queue status
-      const queue = await commands.playerGetQueue();
-      hasNext = queue.hasNext;
-      hasPrevious = queue.hasPrevious;
+      // shuffle/repeat/hasNext/hasPrevious come from the queue store (event-driven).
     } catch (e) {
       // Ignore polling errors
     }