test: the gate's output carries no noise to hide a real warning in

- Home tests mocked the api without downloadIndex, so every card's download button logged a
  missing-queryFn error (64 stderr blocks per run).
- QueryState rendered without an i18n instance; Modal.fullscreen awaited a synchronous act,
  which React reports as an act environment it does not support.
- pytest: Starlette 1.x's TestClient is built on httpx2 and warned on every run without it
  (pinned in requirements-dev); alembic.ini declares its path separator.

frontend/src/components/ui/QueryState.dom.test.tsx

@@ -8,6 +8,9 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { render, cleanup } from "@testing-library/react";
 import { LoadingState } from "./QueryState";
 
+// The label is not under test; without an i18n instance react-i18next warns on every render.
+vi.mock("react-i18next", () => ({ useTranslation: () => ({ t: (key: string) => key }) }));
+
 let now = 0;
 beforeEach(() => {
   vi.spyOn(performance, "now").mockImplementation(() => now);