fix(ui): add initial slide-down transition to FavoritesView

Wrap entire FavoritesView in ViewTransition with direction="down" so the
initial view (header + spinner) slides down on first load.

Complete flow:
0. Initial view appears with slide-down transition (200ms, 12px)
1. Loading spinner shows while syncing
2. When sync completes, spinner fades out (200ms)
3. Content appears with slide-up transition (200ms, 12px)

src/lib/components/views/FavoritesView.svelte

@@ -898,6 +898,7 @@
 
 </script>
 
+<ViewTransition duration={200} distance={12} direction="down">
 <div class="favorites-view" bind:this={scrollContainer}>
   <!-- Header -->
   <div class="header">
@@ -1594,6 +1595,7 @@
     {/if}
   </div>
 </div>
+</ViewTransition>
 
 <FavoritesEditModal
   isOpen={editModalOpen}