Enhance theming and UI components: Introduce a new dark cyan theme in globals.css, update layout to utilize ThemeProvider for consistent theming, and refactor button and card components to use CSS variables for styling. Improve navigation and alert components with dynamic styles based on theme variables, ensuring a cohesive user experience across the application.

components/ui/index.ts

@@ -11,4 +11,5 @@ export { default as SectionTitle } from "./SectionTitle";
 export { default as BackgroundSection } from "./BackgroundSection";
 export { default as Alert } from "./Alert";
 export { default as CloseButton } from "./CloseButton";
+export { default as ThemeToggle } from "./ThemeToggle";