Fix video deduper timestamp comparison

tests/utils/video-deduper.test.mjs

@@ -0,0 +1,23 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { dedupeToNewestByRoot } from "../../js/utils/videoDeduper.js";
+
+test("dedupeToNewestByRoot replaces entries with missing timestamps", () => {
+  const original = { id: "abc", created_at: undefined };
+  const newer = { id: "abc", created_at: 123 };
+
+  const [result] = dedupeToNewestByRoot([original, newer]);
+
+  assert.equal(result, newer);
+});
+
+test("dedupeToNewestByRoot replaces entries with non-numeric timestamps", () => {
+  const rootId = "root-1";
+  const invalid = { id: "old", videoRootId: rootId, created_at: "not-a-number" };
+  const newer = { id: "new", videoRootId: rootId, created_at: "456" };
+
+  const [result] = dedupeToNewestByRoot([invalid, newer]);
+
+  assert.equal(result, newer);
+});