fix: correct CSS import order for Tailwind v4

- Move Google Fonts import before Tailwind directives
- Fix PostCSS build warning
- Ensure proper CSS compilation

NOTE: Dev server must be restarted for changes to take effect

frontend/src/index.css

@@ -1,9 +1,9 @@
+@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&display=swap');
+
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
 
-@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&display=swap');
-
 * {
   box-sizing: border-box;
 }