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/Home.dom.test.tsx

@@ -49,6 +49,7 @@ vi.mock("../lib/api", () => ({
     setState: () => Promise.resolve(),
     watchLaterAdd: () => Promise.resolve(),
     watchLaterRemove: () => Promise.resolve(),
+    downloadIndex: () => Promise.resolve({}), // the cards' download buttons read it
   },
   DISCOVER_BUDGETS: ["short", "medium", "long", "any"],
   discoverCardKey: (c: { source: string; id: string }) => `${c.source}:${c.id}`,

frontend/src/components/Home.pin.dom.test.tsx

@@ -53,6 +53,7 @@ vi.mock("../lib/api", () => ({
     setState: () => Promise.resolve(),
     watchLaterAdd: () => Promise.resolve(),
     watchLaterRemove: () => Promise.resolve(),
+    downloadIndex: () => Promise.resolve({}), // the cards' download buttons read it
     comfortPins: (...a: unknown[]) => comfortPins(...a),
     addComfortPin: (...a: unknown[]) => addComfortPin(...a),
     removeComfortPin: (...a: unknown[]) => removeComfortPin(...a),

frontend/src/components/ui/Modal.fullscreen.dom.test.tsx

@@ -31,7 +31,7 @@ describe("a dialog open while fullscreen is left", () => {
   it("keeps what the viewer had typed in it, and the focus inside it", async () => {
     const stage = document.createElement("div");
     document.body.appendChild(stage);
-    await setFullscreen(stage);
+    setFullscreen(stage);
     render(
       <Modal title="Download" onClose={() => {}}>
         <input aria-label="name" defaultValue="" />
@@ -42,7 +42,7 @@ describe("a dialog open while fullscreen is left", () => {
     field.focus();
     expect(stage.contains(field)).toBe(true);
 
-    await setFullscreen(null); // the browser's own Esc leaves fullscreen; the dialog stays open
+    setFullscreen(null); // the browser's own Esc leaves fullscreen; the dialog stays open
 
     const after = screen.getByLabelText("name") as HTMLInputElement;
     expect(after.value).toBe("my cut");
@@ -78,7 +78,7 @@ describe("a dialog with an autoFocus child", () => {
     const field = screen.getByLabelText("query");
     expect(document.activeElement).toBe(field);
 
-    await setFullscreen(stage); // the player goes fullscreen under the open dialog
+    setFullscreen(stage); // the player goes fullscreen under the open dialog
 
     expect(stage.contains(field)).toBe(true);
     expect(document.activeElement).toBe(field);

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);