chore: remove Letterspace newsletter integration and all LETTERSPACE_* variables

packages/frontend/src/routes/magazine/[slug]/+page.svelte

@@ -9,7 +9,6 @@ import { getAssetUrl } from "$lib/directus";
 import SharingPopup from "$lib/components/sharing-popup/sharing-popup.svelte";
 import Meta from "$lib/components/meta/meta.svelte";
 import PeonyBackground from "$lib/components/background/peony-background.svelte";
-import NewsletterSignup from "$lib/components/newsletter-signup/newsletter-signup-widget.svelte";
 import SharingPopupButton from "$lib/components/sharing-popup/sharing-popup-button.svelte";
 
 const { data } = $props();
@@ -215,8 +214,6 @@ const timeAgo = new TimeAgo("en");
         </Card>
         -->
 
-                <!-- <NewsletterSignup email={data.authStatus.user?.email}/> -->
-
                 <!-- Back to Magazine -->
                 <Button
                     variant="outline"

packages/frontend/src/routes/newsletter/+server.ts

@@ -1,22 +0,0 @@
-import {
-	LETTERSPACE_API_KEY,
-	LETTERSPACE_API_URL,
-	LETTERSPACE_LIST_ID,
-} from "$env/static/private";
-import { json } from "@sveltejs/kit";
-
-export async function POST({ request, fetch }) {
-	const { email } = await request.json();
-	const lists = [LETTERSPACE_LIST_ID];
-
-	await fetch(`${LETTERSPACE_API_URL}/subscribers`, {
-		method: "POST",
-		headers: {
-			"Content-Type": "application/json",
-			"X-API-Key": LETTERSPACE_API_KEY,
-		},
-		body: JSON.stringify({ email, lists }),
-	});
-
-	return json({ email }, { status: 201 });
-}

packages/frontend/src/routes/videos/[slug]/+page.svelte

@@ -16,7 +16,6 @@ import { formatVideoDuration, getUserInitials } from "$lib/utils";
 import { invalidateAll } from "$app/navigation";
 import { toast } from "svelte-sonner";
 import { createCommentForVideo, likeVideo, unlikeVideo, recordVideoPlay, updateVideoPlay } from "$lib/services";
-import NewsletterSignup from "$lib/components/newsletter-signup/newsletter-signup-widget.svelte";
 import SharingPopupButton from "$lib/components/sharing-popup/sharing-popup-button.svelte";
 
 const { data } = $props();
@@ -539,8 +538,6 @@ let showPlayer = $state(false);
           </CardContent>
         </Card> -->
 
-        <!-- <NewsletterSignup /> -->
-
         <!-- Back to Videos -->
         <Button
           variant="outline"