fix(ui): honest tab titles and a download field that names every site

Signed out, the tab read Home's question over the sign-in form; the legal
pages read just "Siftlode". The download field asked only for a YouTube
link although Facebook and the rest download too.

frontend/src/components/NavigationProvider.dom.test.tsx

@@ -11,6 +11,7 @@
 // bookkeeping.
 import { describe, it, expect, afterEach, beforeEach, vi } from "vitest";
 import { renderHook, act, cleanup } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import type { ReactNode } from "react";
 
 // Partial: the provider reads `t` AND `i18n.language` (both feed the document-title effect), and the
@@ -28,8 +29,14 @@ import { NavigationProvider } from "./NavigationProvider";
 import { useNavigation, useNavigationActions } from "./navigationContext";
 import { useBackToClose } from "../lib/history";
 
+import { qk } from "../lib/queryKeys";
+
+// The provider reads the signed-in account (the tab title) from the `me` cache.
+let qc = new QueryClient();
 const wrapper = ({ children }: { children: ReactNode }) => (
-  <NavigationProvider>{children}</NavigationProvider>
+  <QueryClientProvider client={qc}>
+    <NavigationProvider>{children}</NavigationProvider>
+  </QueryClientProvider>
 );
 const render = () =>
   renderHook(() => ({ ...useNavigation(), ...useNavigationActions() }), { wrapper });
@@ -54,6 +61,8 @@ async function openOverlay() {
 }
 
 beforeEach(() => {
+  qc = new QueryClient();
+  qc.setQueryData(qk.me(), { id: 1 });
   localStorage.clear();
   sessionStorage.setItem("siftlode.activeAccount", "1"); // account-scoped page memory
   window.history.replaceState({ sfPage: "feed" }, "", "/");
@@ -65,6 +74,22 @@ afterEach(() => {
   vi.restoreAllMocks();
 });
 
+describe("NavigationProvider · the tab title", () => {
+  // Prod UAT 2026-09-19: signed out, the tab read the Home page's question over the sign-in form.
+  it("is the brand alone while nobody is signed in, the page's name once someone is", async () => {
+    window.history.replaceState({ sfPage: "home" }, "", "/?page=home");
+    qc.setQueryData(qk.me(), null);
+    render();
+    await settle();
+    expect(document.title).toBe("Siftlode");
+
+    act(() => qc.setQueryData(qk.me(), { id: 1 }));
+    await settle();
+    expect(document.title).not.toBe("Siftlode");
+    expect(document.title.endsWith(" · Siftlode")).toBe(true);
+  });
+});
+
 describe("NavigationProvider · setPage's same-page guard", () => {
   it("pushes an entry for a real page change", () => {
     const { result } = render();