Cache session data

The session is always explicitly updated when it changes, cache it on
the client if it has already been loaded.

composables/session.ts

@@ -2,5 +2,8 @@ export const useAccountSession = () => useFetch(
 	"/api/auth/session",
 	{
 		transform: (input) => input === undefined ? false : input,
+		getCachedData(key, nuxtApp) {
+			return nuxtApp.payload.data[key];
+		},
 	}
 );