chore: update Tailwind CSS from 3.4.15, to 4.1.11

- Changed the PostCSS configuration to use '@tailwindcss/postcss' instead of 'tailwindcss'.
- Deleted the Tailwind configuration file as it is no longer needed.

components/ui/separator.tsx

@@ -19,7 +19,7 @@ const Separator = React.forwardRef<
       orientation={orientation}
       className={cn(
         "shrink-0 bg-border",
-        orientation === "horizontal" ? "h-[1px] w-full" : "h-full w-[1px]",
+        orientation === "horizontal" ? "h-px w-full" : "h-full w-px",
         className
       )}
       {...props}