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/lib/components/library/GenericGenreBrowser.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
   import { onMount } from "svelte";
   import { goto } from "$app/navigation";
+  import { navigateBack } from "$lib/utils/navigation";
   import { currentLibrary } from "$lib/stores/library";
   import { auth } from "$lib/stores/auth";
   import SearchBar from "$lib/components/common/SearchBar.svelte";
@@ -125,7 +126,7 @@
       selectedGenre = null;
       genreItems = [];
     } else {
-      goto(config.backPath);
+      navigateBack(config.backPath);
     }
   }