enhancement: Improve LanguageSwitcher UI

[O2sa]

The current LanguageSwitcher component uses a plain HTML <select> element. We want to enhance its UI to match the rest of the application's design system (e.g., using a custom dropdown menu or standardizing it with our custom UI components).

Tasks

• Open components/language-switcher.tsx.
• Replace the native <select> and <option> elements with a more visually appealing custom dropdown component.
• Ensure it continues to support RTL/LTR layouts correctly.