feat!: migrate to TypeScript and implement emulate using Miniflare

Signed-off-by: Pascal Vorwerk <info@fossores.de>

placeholders.d.ts

@@ -0,0 +1,11 @@
+declare module "SERVER" {
+	export { Server } from "@sveltejs/kit";
+}
+
+declare module "MANIFEST" {
+	import { SSRManifest } from "@sveltejs/kit";
+
+	export const manifest: SSRManifest;
+	export const prerendered: Set<string>;
+	export const app_path: string;
+}