Implement account type restricted page

Add allowedAccountTypes page metadata which the authenticated middleware
uses to further restrict the types of accounts that can access the page.

If the account type is insufficent to access the page it will return an
HTTP 403 Forbidden status, which is rendered using the error page.

error.vue

@@ -0,0 +1,21 @@
+<template>
+	<Header />
+	<h1>{{ error.statusCode }} {{ error.statusMessage }}</h1>
+	{{ error.message }}
+</template>
+
+<script setup lang="ts">
+defineProps<{ error: {
+	statusCode: number,
+	fatal: boolean,
+	unhandled: boolean,
+	statusMessage?: string,
+	data?: unknown,
+	cause?: unknown,
+
+	// Undocumented fields
+	url?: string,
+	message?: string,
+	stack?: string,
+} }>()
+</script>