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/channels/WatchedChannels.dom.test.tsx

@@ -59,6 +59,7 @@ vi.mock("../../features/player/PlayerModal", () => ({
 import WatchedChannels from "./WatchedChannels";
 import { qk } from "../../lib/queryKeys";
 import { api, type Video, type WatchedChannel, type WatchedChannels as List } from "../../lib/api";
+import { msg, type NotifText } from "../../lib/notifications";
 
 afterEach(() => {
   cleanup();
@@ -149,8 +150,10 @@ describe("WatchedChannels", () => {
     fireEvent.click(await screen.findByRole("button", { name: "channels.watched.dismiss" }));
     await waitFor(() => expect(h.notify).toHaveBeenCalled());
     expect(dismiss).toHaveBeenCalledWith("UC1");
-    const toast = h.notify.mock.calls[0]![0] as { action: { label: string; onClick: () => void } };
-    expect(toast.action.label).toBe("common.undo");
+    const toast = h.notify.mock.calls[0]![0] as {
+      action: { label: NotifText; onClick: () => void };
+    };
+    expect(toast.action.label).toEqual(msg("common.undo"));
     act(() => toast.action.onClick());
     await waitFor(() => expect(restore).toHaveBeenCalledWith("UC1"));
   });

frontend/src/modules/channels/useChannelActions.tsx

@@ -74,7 +74,7 @@ export function useChannelActions({
         level: "success",
         message: msg("channels.notify.hidden", { name: nameOf(c) }),
         action: {
-          label: t("common.undo"),
+          label: msg("common.undo"),
           onClick: () => patch.mutate({ id: c.id, body: { hidden: false } }),
         },
       });

frontend/src/modules/channels/useWatchedChannelActions.ts

@@ -44,7 +44,7 @@ export function useWatchedChannelActions(onOpenWizard: () => void) {
       notify({
         level: "success",
         message: msg("channels.watched.dismissed", { name: raw(nameOf(c)) }),
-        action: { label: t("common.undo"), onClick: () => restore.mutate(c) },
+        action: { label: msg("common.undo"), onClick: () => restore.mutate(c) },
       });
     },
   });