[v4] Improve source declaration using @source

[Nayeem-XTREME]

When using the tailwind v4, if I need to target the source from node_modules, currently I have to write like this:

@import 'tailwindcss/theme' layer(theme);
@import 'tailwindcss/preflight' layer(base);

@variant dark (&:is(.dark *));

#__next {
  @tailwind utilities;
}

@import './theme.css';

@source '../../../../node_modules/<ui-library>';

@theme {
  --font-body: var(--font-inter);
  --font-ginto: var(--font-ginto);
  --font-jakarta: var(--font-jakarta);
  --font-code: var(--font-source-code-pro);
}

@layer base {
  code,
  code * {
    @apply font-code antialiased;
  }
}

My proposal is to write @source "<ui-library>" instead of explicitly navigating node_modules.