Rearranged import orders for better visibility and readability. Also, cleaned up some of the typescript and JSX by adding appropriate line breaks and spaces, and ensuring the use of semicolons for better punctuation.
This commit introduces a `ThemeProvider` component and a `ThemeBtnSelector` component. The `ThemeProvider` component applies the current theme to all its children. The `ThemeBtnSelector` component provides a dropdown menu that allows users to select a theme ("light", "dark", or "system").