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/lib/listNav.dom.test.tsx

@@ -511,4 +511,54 @@ describe("useListNav · leaving the list, and naming the item (deep-review E11 r
     expect(a0.hasAttribute("aria-label")).toBe(false);
     expect(screen.getByTestId("a1").getAttribute("aria-label")).toBe("title");
   });
+
+  // A Plex poster's open element is the whole card — badges, title, year, rating and summary — and a
+  // season card's holds only the hover caption "Open show": named from that text, every season was
+  // "Open show" (deep-review E11 round 3). The item's own name wins.
+  it("names a card by the name its item gives, over the text of what it opens", () => {
+    function Posters() {
+      const ref = useRef<HTMLDivElement>(null);
+      useListNav(ref, { enabled: true });
+      return (
+        <div ref={ref}>
+          <div {...navItemAttrs(0, "Season 1")} data-testid="p0">
+            <div role="button" tabIndex={0} data-nav-open="">
+              Open show
+            </div>
+          </div>
+        </div>
+      );
+    }
+    render(<Posters />);
+    press("j");
+    expect(screen.getByTestId("p0").getAttribute("aria-label")).toBe("Season 1");
+  });
+
+  // Hide a card, then Undo in the toast that put up: focus on the toast's button is not the reader
+  // leaving the list, and `j` goes on from the card put back (deep-review E11 round 3).
+  it("keeps the slot when focus went to the Undo of a toast", () => {
+    withLayout(
+      (_, n) => ({ left: 0, top: n * 100 }),
+      () => {
+        const page = (ids: number[]) => (
+          <>
+            <div data-toast-region="">
+              <button data-testid="undo">undo</button>
+            </div>
+            <Swappable ids={ids} />
+          </>
+        );
+        const { rerender } = render(page([0, 1, 2, 3]));
+        press("j");
+        press("j");
+        press("j");
+        rerender(page([0, 1, 3]));
+        act(() => screen.getByTestId("undo").focus());
+        rerender(page([0, 1, 2, 3]));
+        act(() => screen.getByTestId("undo").blur());
+        press("j");
+        expect(focused()).toBe("r2");
+      },
+    );
+  });
 });

frontend/src/lib/listNav.ts

@@ -44,9 +44,16 @@ const LIST = "data-nav-list";
 // How long to wait for a virtualized item to mount after asking the list to reveal it.
 const REVEAL_FRAMES = 10;
 
-/** Spread onto an item's ROOT element. */
-export const navItemAttrs = (index: number): { "data-nav-index": number } => ({
+/** Spread onto an item's ROOT element. `name` is what a screen reader calls the item while the keyboard
+ *  is on it (its title) — pass it where the element Enter opens wraps the whole card (a Plex poster:
+ *  badges, year, rating and summary run together), shows a caption that is not the item's name, or
+ *  holds no text at all (deep-review E11 round 3). */
+export const navItemAttrs = (
+  index: number,
+  name?: string | null,
+): { "data-nav-index": number; "data-nav-name"?: string } => ({
   [INDEX]: index,
+  ...(name ? { "data-nav-name": name } : null),
 });
 
 const indexOf = (item: Element): number => Number(item.getAttribute(INDEX));
@@ -133,10 +140,11 @@ function onFocusIn(e: FocusEvent): void {
   if (item && list) last = { list, index: indexOf(item), el: item };
   // Focus went on to page content that is not an item — the search box, a filter chip: the reader
   // left the list, and whatever it shows next (new results) is not "the slot they were in" (deep-review
-  // E11 round 2). A layer opened FROM the item — its menu, a confirm — does not count: focus comes
-  // back from it, and what it did (a hidden card, a deleted row) is the removal the slot is kept for.
-  // Removing the focused node itself fires no focusin.
-  else if (!target?.closest?.('[data-floating-ui-portal], [role="dialog"]')) last = null;
+  // E11 round 2). A layer opened FROM the item — its menu, a confirm, the Undo toast its removal put
+  // up — does not count: focus comes back from it, and what it did (a hidden card, a deleted row, the
+  // card put back) is what the slot is kept for. Removing the focused node itself fires no focusin.
+  else if (!target?.closest?.('[data-floating-ui-portal], [role="dialog"], [data-toast-region]'))
+    last = null;
 }
 
 /** Where `j` (`k`: the item before) lands after the last-focused item left the DOM: the item now in
@@ -171,8 +179,15 @@ function focusItem(el: HTMLElement, reveal = true): void {
       // A card root is a plain <div>: focused, it has no role and no name, and a screen reader read it
       // as an unlabelled run of text. While it holds the focus it is a group named after what Enter
       // opens (deep-review E11 round 2). A row (<tr>) keeps its own role.
+      // The item's own name when it gives one (`navItemAttrs`), else the open element's label or text:
+      // a title link's text is the title (deep-review E11 round 3).
       const open = el.querySelector("[data-nav-open]");
-      const name = (open?.getAttribute("aria-label") || open?.textContent || "").trim();
+      const name = (
+        el.getAttribute("data-nav-name") ||
+        open?.getAttribute("aria-label") ||
+        open?.textContent ||
+        ""
+      ).trim();
       if (
         el.tagName === "DIV" &&
         name &&