Better enum-based caching for preview images

packages/website/src/app.d.ts

@@ -1,12 +1,16 @@
 // See https://kit.svelte.dev/docs/types#app
 // for information about these interfaces
+import type { Middleware } from "polka"
+type Req = Parameters<Middleware>[0]
 declare global {
 	namespace App {
 		// interface Error {}
 		// interface Locals {}
 		// interface PageData {}
 		// interface PageState {}
-		// interface Platform {}
+		interface Platform {
+            req: Req
+        }
 	}
 }