[Feature]: Add dark mode support #4733

I looked into Chakra UI's ColorModeProvider and it seems we could implement dark mode by configuring the ChakraProvider and adding a ColorModeScript.

Possible implementation approach:

• Configure colorMode in theme.ts
• Add ColorModeScript in the main layout
• Implement a toggle button using useColorMode hook

If approved, I can explore the existing theme structure in the repository and prepare a pull request.