feat: add initial styling and layout for portal views

- Created a global CSS file for consistent styling across the application.
- Implemented the Explore, Home, Topics, and various user views with responsive design.
- Added a Login view with OTP functionality and a Checkout view for order processing.
- Developed a NotFound view for handling 404 errors.
- Established a configuration file for Vite with Tailwind CSS integration.

frontend/portal/src/views/order/PaymentView.vue

@@ -0,0 +1,6 @@
+<template>
+  <div class="mx-auto max-w-screen-xl my-8 p-8 bg-white rounded-xl shadow-sm">
+    <h1 class="text-2xl font-bold mb-4">Payment Cashier</h1>
+    <p class="text-slate-400">Order ID: {{ $route.params.id }}</p>
+  </div>
+</template>