Add TailwindCSS utilities and update UI dependencies

Introduce TailwindCSS utilities, animations, and theme configurations to enhance UI styling. Update dependencies to include Radix, clsx, lucide-react, and other utilities for improved design flexibility and component styling. Refactor global CSS, PostCSS config, and utils for streamlined development.

frontend/postcss.config.mjs

@@ -1,5 +1,6 @@
-const config = {
-  plugins: ["@tailwindcss/postcss"],
+/** @type {import('tailwindcss').Config} */
+export default {
+  plugins: {
+    "@tailwindcss/postcss": {},
+  },
 };
-
-export default config;