test(notifications): the center re-says its rows after a switch, a repeat coalesces by content; e2e helper fails with a cause

The center's rows (title, message, refusal, live button) were never rendered across a language
switch, and nothing held the structural compare that coalescing now needs. The channel-link helper
swallowed whatever ended its poll into a bare false: a link that goes away mid-look now counts as
not hit, and no hittable link fails with the poll's own message.

frontend/e2e/channel.spec.ts

@@ -48,7 +48,7 @@ test.describe("channel view", () => {
     // `.first()` here would grab an overscan card ABOVE the viewport, and Playwright's scroll-into-
     // view would move the feed before navigating, so Back would restore that moved position, not
     // the one under test. (This is what made the test fail while the app was in fact correct.)
-    expect(await clickVisibleChannelLink(page)).toBe(true);
+    await clickVisibleChannelLink(page);
     await expect(page.getByTestId("channel-title")).toBeVisible();
     await page.getByTestId("channel-back").click();
     await expect(page.getByTestId("video-card").first()).toBeVisible();