style(layout): apply Figma drawer translucency with backdrop blur

Figma 4164-5336 frame 173 specifies the drawer body as #14131A at 90%
opacity with a 24px background blur. Switch bg-ark-bg to bg-ark-bg/90
backdrop-blur-xl so the underlying page bleeds through softly rather
than being fully masked.

src/layouts/PublicLayout.tsx

@@ -713,7 +713,7 @@ export function PublicLayout() {
       {open ? (
         <div
           ref={menuRef}
-          className={`${headerMenuAnimationClass} fixed inset-x-0 bottom-0 top-[64px] z-50 flex flex-col bg-ark-bg md:top-[70px] min-[1000px]:hidden`}
+          className={`${headerMenuAnimationClass} fixed inset-x-0 bottom-0 top-[64px] z-50 flex flex-col bg-ark-bg/90 backdrop-blur-xl md:top-[70px] min-[1000px]:hidden`}
         >
           <nav className="flex-1 overflow-y-auto px-5 pt-2">
             {(