feat: add next-themes package and update styles

- Added `next-themes` package for theme management.
- Updated various components to use `hsl(var(--foreground))` for color consistency.
- Changed background colors from `bg-white` to `bg-card` in multiple components for better theming support.

Made-with: Cursor

frontend/lib/registry/components/toggle-switch/ToggleSwitchComponent.tsx

@@ -189,7 +189,7 @@ export const ToggleSwitchComponent: React.FC<ToggleSwitchComponentProps> = ({
         </div>
         <span
           style={{
-            color: "#212121",
+            color: "hsl(var(--foreground))",
             // isInteractive 모드에서는 사용자 스타일 우선 적용
             ...(isInteractive && component.style ? component.style : {}),
           }}