fix(i18n): drop the translation notice from the sign-in pages

Eight of ten languages opened the sign-in, registration and profile
take-over pages with the "machine translated" strip above the form, the
first thing a visitor read before having an account. The strip stays in
the app shell, where the language can be changed and a correction
reported; its text is unchanged.

src/components/layout/__tests__/auth-shell-translation-banner.browser.test.tsx

@@ -0,0 +1,70 @@
+/**
+ * The "machine translated" strip is not part of signing in.
+ *
+ * It belongs to the app, where the language can be changed and a correction
+ * reported; on the sign-in, registration and take-over pages it was the first
+ * thing a visitor in eight of ten languages read, above the form.
+ */
+import { describe, expect, it, vi } from "vitest";
+
+import { renderWithApp } from "../../../../tests/browser/render";
+import { stubFetch } from "../../../../tests/browser/fetch-stub";
+
+// Chrome that is not the subject.
+vi.mock("../sidebar-nav", () => ({ SidebarNav: () => null }));
+vi.mock("../bottom-nav", () => ({ BottomNav: () => null }));
+vi.mock("../top-bar", () => ({ TopBar: () => null }));
+vi.mock("../offline-banner", () => ({ OfflineBanner: () => null }));
+vi.mock("../shared-record-banner", () => ({ SharedRecordBanner: () => null }));
+vi.mock("@/components/gamification/achievement-unlock-notifier", () => ({
+  AchievementUnlockNotifier: () => null,
+}));
+vi.mock("@/components/insights/layout-coach-fab", () => ({
+  LayoutCoachFab: () => null,
+}));
+vi.mock("@/components/insights/layout-coach-mount", () => ({
+  LayoutCoachMount: () => null,
+}));
+vi.mock("@/components/onboarding/tour-launcher", () => ({
+  TourLauncher: () => null,
+}));
+vi.mock("@/components/day/day-layer", () => ({ DayLayerMount: () => null }));
+vi.mock("@/components/command-palette/command-palette.lazy", () => ({
+  CommandPaletteMount: () => null,
+}));
+vi.mock("../global-shortcuts", () => ({ GlobalShortcuts: () => null }));
+
+import { AuthShell } from "../auth-shell";
+
+const BANNER = '[data-slot="maintainership-banner"]';
+
+async function mountAt(path: string, user: { id: string } | null) {
+  window.history.replaceState(null, "", path);
+  await renderWithApp(
+    <AuthShell>
+      <div data-slot="page" />
+    </AuthShell>,
+    { user, locale: "fr" },
+  );
+  await expect
+    .poll(() => document.querySelector('[data-slot="page"]'))
+    .toBeTruthy();
+}
+
+describe("translation notice", () => {
+  it("is not shown on the sign-in page", async () => {
+    stubFetch().on("GET", "/api/auth/me", {
+      status: 401,
+      error: "Unauthorized",
+    });
+    await mountAt("/auth/login", null);
+    await new Promise((resolve) => setTimeout(resolve, 100));
+    expect(document.querySelector(BANNER)).toBeNull();
+  });
+
+  it("is still shown inside the app", async () => {
+    stubFetch();
+    await mountAt("/", { id: "signed-in" });
+    await expect.poll(() => document.querySelector(BANNER)).toBeTruthy();
+  });
+});

src/components/layout/auth-shell.tsx

@@ -342,7 +342,6 @@ export function AuthShell({
     return (
       <div className="flex min-h-dvh flex-col pt-[env(safe-area-inset-top,0px)] pr-[env(safe-area-inset-right,0px)] pb-[env(safe-area-inset-bottom,0px)] pl-[env(safe-area-inset-left,0px)]">
         {demoMode ? <DemoBanner /> : null}
-        <MaintainershipBanner />
         <main
           id="main-content"
           className="flex flex-1 items-center justify-center px-4 py-6"