Add light/dark mode toggle to navbar (lucide-react + localStorage)

[jikrana1]

Add a theme toggle icon (Sun/Moon from lucide-react) in the navbar.

• Click toggles between light and dark mode
• Save user preference in localStorage to persist across sessions
  Can you please assign this issue to me? I'd like to work on it.

[rishima17]

@jikrana1 I’ve assigned it to you. Feel free to star the repo if you like the work ⭐

[jikrana1]

Thank you for your response. I will now take care of solving this issue.