feat(utils): add utility function for class merging

A new utility function `cn` has been added to `utils.ts` for the purpose of class merging. This function uses "clsx" and "tailwind-merge" to merge class values, simplifying and optimizing the process of multiple class joining in our project.

src/lib/utils.ts

@@ -0,0 +1,6 @@
+import { type ClassValue, clsx } from "clsx"
+import { twMerge } from "tailwind-merge"
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs))
+}