fix(web): drop backdrop-blur from Pill card overlay preset (#89)

The Pill overlay preset was the only one of the five to carry
`backdrop-blur-sm` (backdrop-filter: blur(4px)) on its badge class.
Each enabled badge renders its own element, so a typical library grid
produces hundreds of backdrop-filter layers the browser must re-sample
and blur on every repaint — including every scroll frame, since the
poster art behind each badge moves while scrolling. This caused severe
scroll/interaction jank, most visibly on Chrome on Windows.

The blur is also effectively invisible: the Pill background is already
rgba(20,20,30,0.7) (70% opaque), so removing it has no meaningful visual
impact while eliminating the per-frame GPU cost. The other four presets
are unaffected.

web/src/lib/overlays/presets.ts

@@ -60,7 +60,7 @@ export const OVERLAY_PRESETS: Record<PresetId, OverlayPreset> = {
     label: "Pill",
     description: "Larger pill with more padding. Works well with icons.",
     badgeClass:
-      "rounded-full border border-white/15 px-2.5 py-1 text-[10px] font-semibold tracking-wide uppercase leading-none backdrop-blur-sm",
+      "rounded-full border border-white/15 px-2.5 py-1 text-[10px] font-semibold tracking-wide uppercase leading-none",
     badgeStyle: (accent) => ({
       background: accent
         ? `color-mix(in srgb, ${accent} 20%, rgba(20,20,30,0.7))`