fix(nav): prevent style dropdown from closing hamburger menu

Stop click event propagation from the nested AbacusDisplayDropdown
to prevent it from closing the parent hamburger menu.

Added stopPropagation to:
- Style dropdown trigger button
- Style dropdown content wrapper

This allows the nested dropdown to function independently without
affecting the parent menu state.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/web/src/components/AbacusDisplayDropdown.tsx

@@ -26,6 +26,7 @@ export function AbacusDisplayDropdown({ isFullscreen = false }: AbacusDisplayDro
     <DropdownMenu.Root open={open} onOpenChange={handleOpenChange}>
       <DropdownMenu.Trigger asChild>
         <button
+          onClick={(e) => e.stopPropagation()} // Prevent parent dropdown from closing
           className={css({
             display: 'flex',
             alignItems: 'center',
@@ -75,6 +76,7 @@ export function AbacusDisplayDropdown({ isFullscreen = false }: AbacusDisplayDro
 
       <DropdownMenu.Portal>
         <DropdownMenu.Content
+          onClick={(e) => e.stopPropagation()} // Prevent clicks inside from closing parent
           className={css({
             bg: isFullscreen ? 'rgba(0, 0, 0, 0.85)' : 'white',
             rounded: 'xl',