feat: themed scrollbars and chiseled thumbnail chips

- Replace browser scrollbars with slim 6px overlay pills that tint to
  primary on hover (transparent track, Firefox + WebKit).
- Rework the thumbnail badge family: drop the mismatched white ring
  halo for a 1px dark frame + inset top highlight, and swap rounded-
  full pills for rounded-sm chips so the ornaments match the pixel-art
  aesthetic used elsewhere in the app.
- Soften the ActiveHeapCard desert backdrop so the fanned thumbnails
  read on top.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/timeline/PhotoThumbnail.tsx

@@ -11,20 +11,29 @@ export const PHOTO_DRAG_MIME = 'application/x-mulita-photos'
 // ── Thumbnail badge family ───────────────────────────────────────────────
 // Every ornament that overlays a thumbnail — here and in other views that
 // wrap PhotoThumbnail (e.g. DuplicatesView) — must compose these classes so
-// the set reads as one coherent system. Shape, height, ring, typography are
-// fixed; only the colour variant varies by semantics:
+// the set reads as one coherent system. Shape, height, typography are
+// fixed; variants set the fill + chiseled-pixel frame:
 //   PRIMARY  → user-affirmed state (selection, rating, active-heap)
 //   NEUTRAL  → informational metadata (duplicate flag, discard, file type, dims)
 //   PICK     → auto-suggested "best" in duplicate groups
+//
+// Frame is a single box-shadow stack rather than a Tailwind `ring` so the
+// 1px outline, the subtle inset top highlight, and the drop shadow all
+// live in one paint, and variants can tint the inset highlight to suit
+// their fill. Corners are `rounded-sm` (2px) to echo the pixel-art theme
+// used in the TopBar and ActiveHeapCard.
 export const THUMB_BADGE_BASE =
-  'inline-flex h-5 items-center gap-1 rounded-full px-1.5 text-[10px] font-medium leading-none text-white shadow-md ring-1 ring-white/90'
+  'inline-flex h-5 items-center gap-1 rounded-sm px-1.5 text-[10px] font-semibold leading-none text-white'
 /** Square icon-only variant — compose alongside THUMB_BADGE_BASE. */
 export const THUMB_BADGE_SQUARE = 'w-5 justify-center !px-0'
 /** Standard icon size for any lucide glyph inside a badge. */
 export const THUMB_BADGE_ICON = 'h-3 w-3'
-export const THUMB_BADGE_PRIMARY = 'bg-primary'
-export const THUMB_BADGE_NEUTRAL = 'bg-black/70 backdrop-blur-sm'
-export const THUMB_BADGE_PICK = 'bg-pick'
+export const THUMB_BADGE_PRIMARY =
+  'bg-primary shadow-[0_0_0_1px_rgba(0,0,0,0.55),inset_0_1px_0_rgba(255,255,255,0.28),0_1px_2px_rgba(0,0,0,0.5)]'
+export const THUMB_BADGE_NEUTRAL =
+  'bg-black/75 backdrop-blur-sm shadow-[0_0_0_1px_rgba(255,255,255,0.12),inset_0_1px_0_rgba(255,255,255,0.08),0_1px_2px_rgba(0,0,0,0.55)]'
+export const THUMB_BADGE_PICK =
+  'bg-pick shadow-[0_0_0_1px_rgba(0,0,0,0.55),inset_0_1px_0_rgba(255,255,255,0.28),0_1px_2px_rgba(0,0,0,0.5)]'
 
 // Auto-retry schedule (ms). Backend generates thumbs on-demand via Celery, so
 // the first hit on a freshly-scanned library returns 404 "not ready" until
@@ -135,7 +144,7 @@ export function PhotoThumbnail({
   useEffect(() => {
     return () => clearRetryTimer()
   }, [])
-  
+
   // Build the drag payload at fire time so multi-selection drags carry the
   // current selection. If the dragged photo isn't part of the selection,
   // drag just that one photo (matches Finder semantics).
@@ -160,7 +169,7 @@ export function PhotoThumbnail({
         // pops on light AND dark photos.
         'hover:ring-2 hover:ring-primary/60 hover:ring-offset-1 hover:ring-offset-bg',
         isSelected &&
-          'ring-2 ring-primary ring-offset-2 ring-offset-bg shadow-lg',
+        'ring-2 ring-primary ring-offset-2 ring-offset-bg shadow-lg',
         !imageLoaded && 'bg-surface animate-pulse'
       )}
       style={
@@ -222,7 +231,7 @@ export function PhotoThumbnail({
           </div>
         </div>
       )}
-      
+
       {/* ── Ornaments ────────────────────────────────────────────────────
        *  All overlays compose the THUMB_BADGE_* classes so they share one
        *  shape/size/ring family. Colour signals semantics:
@@ -297,10 +306,10 @@ export function PhotoThumbnail({
       {/* TR — file-type metadata (RAW / VIDEO) */}
       {(photo.filepath.toLowerCase().match(/\.(raw|arw|cr2|cr3|nef|orf|rw2|dng)$/i) ||
         photo.filepath.toLowerCase().match(/\.(mov|mp4|avi|mkv)$/i)) && (
-        <div className={clsx('absolute right-1 top-1', THUMB_BADGE_BASE, THUMB_BADGE_NEUTRAL)}>
-          {photo.filepath.toLowerCase().match(/\.(mov|mp4|avi|mkv)$/i) ? 'VIDEO' : 'RAW'}
-        </div>
-      )}
+          <div className={clsx('absolute right-1 top-1', THUMB_BADGE_BASE, THUMB_BADGE_NEUTRAL)}>
+            {photo.filepath.toLowerCase().match(/\.(mov|mp4|avi|mkv)$/i) ? 'VIDEO' : 'RAW'}
+          </div>
+        )}
     </div>
   )
 }