fix: Add default websiteUrl through .env

Author: Ushie

.env.example

@@ -1,3 +1,4 @@
 RV_API_URL=
+RV_WEBSITE_URL=
 RV_DMCA_GUID=
 RV_GOOGLE_TAG_MANAGER_ID=

src/routes/+page.svelte

@@ -2,13 +2,13 @@
 	import { onMount } from 'svelte';
 
 	import type { BackendAbout } from '$types';
-	import { RV_API_URL } from '$env/static/public';
+	import { RV_API_URL, RV_WEBSITE_URL } from '$env/static/public';
 
 	import Footer from '$components/organisms/Footer.svelte';
 	import Embed from '$components/molecules/Embed.svelte';
 
 	let about = $state<BackendAbout | null>(null);
-	let websiteUrl = $state<string | undefined>(undefined);
+	let websiteUrl = $state<string | undefined>(RV_WEBSITE_URL);
 	let referrer = $state<string | null>(null);
 
 	async function fetchAbout() {