test: assert folder archive removal on downgrade

tests/conversation-home-items.test.ts

@@ -329,6 +329,10 @@ test("conversation home upgrades and downgrades a folder archive as thread count
 
   assert.ok(direct, "expected a single remaining thread to downgrade back to direct");
   assert.equal(direct?.conversationType, "single_device");
+  assert.equal(
+    items.some((item) => item.conversationType === "folder_archive" && item.folderKey === "mac-studio:boss"),
+    false,
+  );
 });
 
 test("conversation home groups multiple imported threads by folder while keeping single-thread projects direct", async () => {