feat(favorites): add bulk make-offline action to track selection bar

Add CloudDownload button to BulkActionBar for downloading selected
tracks for offline use. Fires v2_cache_favorite_track for each
selected track.

Closes #231

cc

src/lib/components/BulkActionBar.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { ListPlus, ListEnd, ListMusic, Heart, HeartOff, Trash2, X, ChevronDown } from 'lucide-svelte';
+  import { ListPlus, ListEnd, ListMusic, Heart, HeartOff, Trash2, X, ChevronDown, CloudDownload } from 'lucide-svelte';
   import { t } from 'svelte-i18n';
 
   interface Props {
@@ -10,6 +10,7 @@
     onAddFavorites?: () => void;
     onRemoveFavorites?: () => void;
     onRemoveFromPlaylist?: () => void;
+    onMakeOffline?: () => void;
     onClearSelection: () => void;
     placement?: 'top' | 'bottom';
   }
@@ -22,6 +23,7 @@
     onAddFavorites,
     onRemoveFavorites,
     onRemoveFromPlaylist,
+    onMakeOffline,
     onClearSelection,
     placement = 'bottom',
   }: Props = $props();
@@ -92,6 +94,13 @@
         <span>{$t('actions.addToPlaylist')}</span>
       </button>
 
+      {#if onMakeOffline}
+        <button class="action-btn" onclick={onMakeOffline} title={$t('actions.makeAvailableOffline')}>
+          <CloudDownload size={15} />
+          <span>{$t('actions.makeAvailableOffline')}</span>
+        </button>
+      {/if}
+
       {#if onAddFavorites}
         <button class="action-btn" onclick={onAddFavorites} title={$t('actions.addToFavorites')}>
           <Heart size={15} />

src/lib/components/views/FavoritesView.svelte

@@ -301,6 +301,14 @@
     selectedTrackIds = new Set();
   }
 
+  async function handleBulkMakeOffline() {
+    for (const id of selectedTrackIds) {
+      invoke('v2_cache_favorite_track', { trackId: id }).catch(() => {});
+    }
+    trackSelectMode = false;
+    selectedTrackIds = new Set();
+  }
+
   let albumViewMode = $state<'grid' | 'list'>('grid');
   type AlbumGroupMode = 'alpha' | 'artist';
   let albumGroupMode = $state<AlbumGroupMode>('alpha');
@@ -1724,6 +1732,7 @@
           onPlayNext={handleBulkPlayNext}
           onPlayLater={handleBulkPlayLater}
           onAddToPlaylist={handleBulkAddToPlaylist}
+          onMakeOffline={handleBulkMakeOffline}
           onRemoveFavorites={handleBulkRemoveFavorites}
           onClearSelection={() => { selectedTrackIds = new Set(); }}
         />