refactor: migrate admin pages and components to new design system

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/admin/ActionMenu.tsx

@@ -53,8 +53,8 @@ export function ActionMenu({ items }: ActionMenuProps) {
         ref={buttonRef}
         onClick={() => setOpen(!open)}
         className={cn(
-          'rounded-md p-1.5 text-white/50 transition-colors',
-          'hover:bg-white/10 hover:text-white'
+          'rounded-md p-1.5 text-muted-foreground transition-colors',
+          'hover:bg-accent hover:text-foreground'
         )}
       >
         <MoreHorizontal className="h-4 w-4" />
@@ -63,8 +63,8 @@ export function ActionMenu({ items }: ActionMenuProps) {
         <div
           ref={menuRef}
           className={cn(
-            'fixed z-50 min-w-[160px] rounded-md border border-white/10',
-            'bg-black py-1 shadow-lg animate-scale-in'
+            'fixed z-50 min-w-[160px] rounded-md border border-border',
+            'bg-card py-1 shadow-lg animate-scale-in'
           )}
           style={{
             top: `${menuPosition.top}px`,
@@ -81,7 +81,7 @@ export function ActionMenu({ items }: ActionMenuProps) {
                 'disabled:opacity-50 disabled:pointer-events-none',
                 item.destructive
                   ? 'text-red-400 hover:bg-red-400/10'
-                  : 'text-white/70 hover:bg-white/[0.06]'
+                  : 'text-muted-foreground hover:bg-accent'
               )}
             >
               {item.icon}