diigo-cache: test that a cached page replays fetch-time order

A hit must replay diigo's order as fetched (page_members.pos), not a
column sort. The fake webapp's link_id and updated_at are scrambled so
neither column sorts back into diigo's order; ordering the replay by
updated or item_id fails the new test.

Generated-by: Claude Opus 5.5

diigo-cache/tests/fake-webapp.js

@@ -10,10 +10,13 @@ import { RpcTarget, WorkerEntrypoint } from "cloudflare:workers";
 const KNOWN_WEBAPP = "fake-webapp-id";
 const TOTAL = 30;
 
-/** item n (1-based, updated-desc order): diigo's field names, made-up values */
+/** item n (1-based, in diigo's order): diigo's field names, made-up
+ * values. link_id and updated_at are scrambled (distinct; 7 and 11 are
+ * coprime to 31), so neither column sorts back into diigo's order — a
+ * cache that replays by column rather than by fetch order is caught. */
 function item(n) {
 	return {
-		link_id: 1000 + n,
+		link_id: 1000 + ((n * 7) % 31),
 		url: `https://example.com/${n}`,
 		title: `bookmark ${n}`,
 		description: "",
@@ -23,7 +26,7 @@ function item(n) {
 		user_id: 4242,
 		tags: "",
 		created_at: 1700000000,
-		updated_at: 1700001000 - n,
+		updated_at: 1700001000 + ((n * 11) % 31),
 	};
 }