feat(cli): add polar as better-auth plugin (#578)

apps/cli/templates/payments/polar/web/nuxt/app/pages/success.vue.hbs

@@ -0,0 +1,11 @@
+<script setup lang="ts">
+const route = useRoute()
+const checkout_id = route.query.checkout_id as string
+</script>
+
+<template>
+  <div class="container mx-auto px-4 py-8">
+    <h1 class="text-2xl font-bold mb-4">Payment Successful!</h1>
+    <p v-if="checkout_id">Checkout ID: \{{ checkout_id }}</p>
+  </div>
+</template>