feat(ui): show active download count in navigation

src/routes/+layout.svelte

@@ -5,11 +5,20 @@
   import ToolBar from "$lib/ToolBar.svelte";
   import { settings, loadSettings } from '$lib/stores/settings';
   import { scanPlaylists, type Playlist } from '$lib/library/scanner';
+  import { downloadQueue } from '$lib/stores/downloadQueue';
 
   let { children } = $props();
 
   let playlists = $state<Playlist[]>([]);
 
+  // Count active downloads (queued or downloading)
+  let activeDownloads = $derived(
+    $downloadQueue.queueOrder.filter(id => {
+      const item = $downloadQueue.queue[id];
+      return item && (item.status === 'queued' || item.status === 'downloading');
+    }).length
+  );
+
   onMount(async () => {
     await loadSettings();
     await loadPlaylists();
@@ -46,7 +55,7 @@
       </a>
       <a href="/downloads" class="nav-item">
         <img src="/icons/cd-audio.png" alt="" class="nav-icon" />
-        Downloads
+        Downloads{#if activeDownloads > 0} ({activeDownloads}){/if}
       </a>
       <details class="nav-collapsible">
          <summary class="nav-item">