Fix Tailwind CSS v4 configuration

- Update src/index.css to use @import "tailwindcss" (v4 syntax)
- Remove tailwind.config.js (not needed in v4)
- Tailwind styles now properly applied

src/index.css

@@ -1,3 +1 @@
-@tailwind base;
-@tailwind components;
-@tailwind utilities;
+@import "tailwindcss";