feat: restructure styles and components for improved design system

- Added typography and design system styles to globals.css.
- Removed deprecated home.css and landing.css files.
- Introduced DiscordSignInButton component for Discord authentication.
- Created Card and CardGrid components for structured content display.
- Implemented ContainerShowcase to demonstrate card usage and layout.
- Added DesignSystemTabs for navigation between design system sections.
- Established typography.css for consistent text styling across components.
- Added tests for typography styles to ensure compliance with design standards.

styles/globals.css

@@ -3,6 +3,8 @@
 @import "tailwindcss/theme.css" layer(theme);
 @import "tailwindcss/utilities.css" layer(utilities);
 @import "tw-animate-css";
+@import "./typography.css";
+@import "./design-system.css" layer(components);
 
 @custom-variant dark (&:is(.dark *));