fix(keys): epic-end review round 3 — the part-way clip count shows, busy buttons keep focus, cards say their names

Targeted round over 3cd0c525's fix surfaces: 14 raised, 14 fixed.

- VideoEditor: the "only X of Y clips" toast went silent exactly on the job-cap/quota refusal it was
  written for (req had already reported the error); it now always shows. The cut list holds still while
  Create queues, and a retry continues the "(i/N)" series.
- ChannelPage: Subscribe/Unsubscribe use Button `loading`, "Load more" and ChannelDiscovery's Subscribe
  block the click with aria-disabled instead of native disabled; busy Block/Hide no longer light up on
  hover.
- listNav: an item can name itself (`navItemAttrs(i, name)`) — Plex posters, seasons, episodes, message
  rows and download rows pass their title; focus on a toast's Undo keeps the removed card's slot.
- AnchoredPopover: the hand-back only for focus-managed surfaces (a hover card no longer pulls focus
  back); the dead panel-ref check is gone.
- AccountPanel: no confirmation mail offered to the demo account; send_failed copy no longer blames
  the message for an unreachable server. Pager comment points at scrollParent.

frontend/src/components/accountPanel.dom.test.tsx

@@ -63,12 +63,12 @@ const user = {
   is_suspended: false,
 };
 
-function mount() {
+function mount(u: typeof user = user) {
   const qc = new QueryClient({ defaultOptions: { queries: { retry: false } } });
   render(
     <QueryClientProvider client={qc}>
       {/* eslint-disable-next-line @typescript-eslint/no-explicit-any */}
-      <AccountPanel user={user as any} onClose={() => {}} />
+      <AccountPanel user={u as any} onClose={() => {}} />
     </QueryClientProvider>,
   );
 }
@@ -148,3 +148,15 @@ describe("the account panel reports a refused recovery action", () => {
     await waitFor(() => expect(errorMessages()).toContain("users.pendingAccess.activateFailed"));
   });
 });
+
+describe("the account panel on the demo account", () => {
+  // The demo account's address is never confirmed, so "send the confirmation link again" looked
+  // available — and the server refused it as "nothing left to confirm", beside a row reading
+  // "unconfirmed" (deep-review E11 round 3).
+  it("does not offer it a confirmation mail, which the server refuses", async () => {
+    mount({ ...user, is_demo: true });
+    await screen.findByText("users.account.recovery");
+    const resend = screen.getByText("users.account.resend").closest("button")!;
+    expect(resend.hasAttribute("disabled")).toBe(true);
+  });
+});