feat: 0.1.1 — timeline scrubber, gallery virtualisation, folder reorder, QoL polish

Timeline:
- Add a right-edge scrubber (year labels + month dots) that jumps to any
  period; runs in the same direction as the scrolled content
- Load the full filtered set in Timeline view so the scrubber spans the whole
  library instead of just the first page

Gallery & UI:
- Virtualise the gallery grid
- Folder reordering in the sidebar (drag + persisted sort_order) and a themed
  dropdown component
- Subtle Light theme contrast fixes for toggles, secondary buttons and the
  update toast

Embedding workers now defer video jobs without a thumbnail at claim time and
requeue any previously-failed deferred jobs on startup, so videos no longer
churn through failed embeddings.

QoL polish across BackgroundTasks, DuplicateFinder, Lightbox and VideoPlayer.

src/components/DuplicateFinder.tsx

@@ -165,7 +165,7 @@ export function DuplicateFinder() {
     : null;
 
   return (
-    <div className="flex min-h-0 flex-1 flex-col overflow-hidden bg-[#07080f]">
+    <div className="flex min-h-0 flex-1 flex-col overflow-hidden bg-gray-950">
       {/* Header */}
       <div className="shrink-0 border-b border-white/[0.05] px-6 py-4">
         <div className="flex items-center justify-between gap-4">