fix(notifications): a notice's button is said when shown, like its text

An action label was translated when the notice was raised, so after a language switch a live
toast or center row read in one language with its button in the other. The access-requests nudge
no longer re-issues on a switch for it. New tests: the button and a server refusal follow a
switch.

frontend/src/modules/plex/usePlexPlaylistEdits.dom.test.tsx

@@ -15,8 +15,11 @@ vi.mock("react-i18next", async (importOriginal) => ({
 }));
 const { notify } = vi.hoisted(() => ({
   notify: vi.fn(
-    (_n: { level: string; message: NotifText; action?: { label: string; onClick: () => void } }) =>
-      0,
+    (_n: {
+      level: string;
+      message: NotifText;
+      action?: { label: NotifText; onClick: () => void };
+    }) => 0,
   ),
 }));
 vi.mock("../../lib/notifications", async (importOriginal) => ({
@@ -149,7 +152,7 @@ describe("usePlexPlaylistEdits · the removal", () => {
     expect(toast.message).toEqual(
       msg("plex.playlist.removedToast", { title: raw("Show · Season 1") }),
     );
-    expect(toast.action!.label).toBe("common.undo");
+    expect(toast.action!.label).toEqual(msg("common.undo"));
     act(() => toast.action!.onClick());
     await waitFor(() => expect(add).toHaveBeenCalledTimes(1));
     expect(add).toHaveBeenCalledWith(5, ["2", "4"], [1, 3]);

frontend/src/modules/plex/usePlexPlaylistEdits.ts

@@ -13,7 +13,7 @@ import { reinsertAt } from "../../lib/reinsert";
  *  Split from `PlexPlaylistView` so the failure paths are reachable from a test: the reorder is
  *  driven by a dnd-kit drag, and neither of its sensors activates under jsdom. */
 export function usePlexPlaylistEdits(playlistId: number) {
-  const { t, i18n } = useTranslation();
+  const { i18n } = useTranslation();
   const qc = useQueryClient();
   const [busy, setBusy] = useState(false);
   // The rows' titles are in the reader's language, so the cache entry is per language — and ONE
@@ -112,7 +112,7 @@ export function usePlexPlaylistEdits(playlistId: number) {
       level: "success",
       message: msg("plex.playlist.removedToast", { title }),
       action: {
-        label: t("common.undo"),
+        label: msg("common.undo"),
         onClick: () =>
           void qc
             .fetchQuery({