feat: add Tailwind CSS and PostCSS configuration

- Created postcss.config.js to configure PostCSS with Tailwind CSS and Autoprefixer.
- Updated svelte.config.js to enable PostCSS preprocessing.
- Added tailwind.config.js for Tailwind CSS configuration.
- Updated yarn.lock to include new dependencies for Tailwind CSS, PostCSS, and related plugins.

frontend/src/App.svelte

@@ -37,8 +37,15 @@
     })
 </script>
 
-<h1>Tibi Svelte Starter</h1>
-
-<style lang="less" global>
-    @import "./css/style.less";
-</style>
+<header class="text-white p-4 bg-red-900">
+    <div class="container mx-auto flex justify-between items-center">
+        <a href="/" class="text-xl font-bold">Tibi Svelte Starter</a>
+        <nav>
+            <ul class="flex space-x-4">
+                <li><a href="/" class="hover:underline">Home</a></li>
+                <li><a href="/about" class="hover:underline">About</a></li>
+                <li><a href="/contact" class="hover:underline">Contact</a></li>
+            </ul>
+        </nav>
+    </div>
+</header>

frontend/src/css/style.css

@@ -0,0 +1,3 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;

frontend/src/index.ts

@@ -1,3 +1,4 @@
+import "./css/style.css"
 import App from "./App.svelte"
 import { hydrate } from "svelte"