fix(notifications): a confirm names its user and channel again; t() and a notice's text are kept apart by a contract

The value sweep wrapped two plain t() values in raw(), so the delete-user and the YouTube subscribe
confirms read "[object Object]" where the email or the channel was. tsc cannot see that seam, so a
syntax contract now refuses a notice value handed to t() and an already-said text kept in a notice.
The raw() doc says what it is: text kept as fetched (a Plex title in the language it was fetched in).
seasonTitleText's no-number branches are tested.

frontend/src/modules/channels/useWatchedChannelActions.confirm.dom.test.tsx

@@ -0,0 +1,39 @@
+// @vitest-environment jsdom
+//
+// Subscribing changes the reader's real YouTube account, so the confirm names the channel it
+// subscribes to — in both languages, through the real i18n. A notice's value (`raw`, `msg`) is said
+// only by sayNotif: handed to a plain `t()` it reads "[object Object]".
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { act, cleanup, renderHook } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import type { ReactNode } from "react";
+import i18n from "../../i18n";
+
+const h = vi.hoisted(() => ({ confirm: vi.fn(async (_o: { message: string }) => false) }));
+vi.mock("../../components/ui/confirmContext", () => ({ useConfirm: () => h.confirm }));
+
+import { useWatchedChannelActions } from "./useWatchedChannelActions";
+import type { WatchedChannel } from "../../lib/api";
+
+afterEach(async () => {
+  cleanup();
+  h.confirm.mockClear();
+  await i18n.changeLanguage("en");
+});
+
+const channel = { id: "UC1", title: "Kurzgesagt" } as WatchedChannel;
+
+const wrapper = ({ children }: { children: ReactNode }) => (
+  <QueryClientProvider client={new QueryClient()}>{children}</QueryClientProvider>
+);
+
+describe("the subscribe confirm", () => {
+  it.each(["en", "hu"])("names the channel (%s)", async (lng) => {
+    await i18n.changeLanguage(lng);
+    const { result } = renderHook(() => useWatchedChannelActions(() => {}), { wrapper });
+    await act(() => result.current.onSubscribe(channel));
+    const said = h.confirm.mock.lastCall![0].message;
+    expect(said).toContain("Kurzgesagt");
+    expect(said).not.toContain("[object Object]");
+  });
+});

frontend/src/modules/channels/useWatchedChannelActions.ts

@@ -54,7 +54,7 @@ export function useWatchedChannelActions(onOpenWizard: () => void) {
   const onSubscribe = async (c: WatchedChannel): Promise<boolean> => {
     const ok = await confirm({
       title: t("channels.discovery.subscribe"),
-      message: t("channels.discovery.confirmSubscribe", { name: raw(nameOf(c)) }),
+      message: t("channels.discovery.confirmSubscribe", { name: nameOf(c) }),
       confirmLabel: t("channels.discovery.subscribe"),
     });
     if (ok) subscribe.mutate(c);