feat: secure and document book reviews system

Added rate limiting to APIs, cleaned up docs, implemented fallback logic for reviews without text, and added comprehensive n8n guide.

app/__tests__/components/CurrentlyReading.test.tsx

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+import { render, screen, waitFor } from "@testing-library/react";
+import CurrentlyReading from "@/app/components/CurrentlyReading";
+
+// Mock next-intl
+jest.mock("next-intl", () => ({
+  useTranslations: () => (key: string) => {
+    const translations: Record<string, string> = {
+      title: "Reading",
+      progress: "Progress",
+    };
+    return translations[key] || key;
+  },
+}));
+
+// Mock next/image
+jest.mock("next/image", () => ({
+  __esModule: true,
+  default: (props: any) => <img {...props} />,
+}));
+
+// Mock fetch
+global.fetch = jest.fn();
+
+describe("CurrentlyReading Component", () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it("renders nothing when loading", () => {
+    // Return a never-resolving promise to simulate loading state
+    (global.fetch as jest.Mock).mockReturnValue(new Promise(() => {}));
+    const { container } = render(<CurrentlyReading />);
+    expect(container).toBeEmptyDOMElement();
+  });
+
+  it("renders nothing when no books are returned", async () => {
+    (global.fetch as jest.Mock).mockResolvedValue({
+      ok: true,
+      json: async () => ({ currentlyReading: null }),
+    });
+
+    const { container } = render(<CurrentlyReading />);
+    await waitFor(() => expect(global.fetch).toHaveBeenCalled());
+    expect(container).toBeEmptyDOMElement();
+  });
+
+  it("renders a book when data is fetched", async () => {
+    const mockBook = {
+      title: "Test Book",
+      authors: ["Test Author"],
+      image: "/test-image.jpg",
+      progress: 50,
+      startedAt: "2023-01-01",
+    };
+
+    (global.fetch as jest.Mock).mockResolvedValue({
+      ok: true,
+      json: async () => ({ currentlyReading: mockBook }),
+    });
+
+    render(<CurrentlyReading />);
+
+    await waitFor(() => {
+      expect(screen.getByText("Reading (1)")).toBeInTheDocument();
+      expect(screen.getByText("Test Book")).toBeInTheDocument();
+      expect(screen.getByText("Test Author")).toBeInTheDocument();
+      expect(screen.getByText("50%")).toBeInTheDocument();
+    });
+  });
+
+  it("renders multiple books correctly", async () => {
+    const mockBooks = [
+      {
+        title: "Book 1",
+        authors: ["Author 1"],
+        image: "/img1.jpg",
+        progress: 10,
+        startedAt: "2023-01-01",
+      },
+      {
+        title: "Book 2",
+        authors: ["Author 2"],
+        image: "/img2.jpg",
+        progress: 90,
+        startedAt: "2023-02-01",
+      },
+    ];
+
+    (global.fetch as jest.Mock).mockResolvedValue({
+      ok: true,
+      json: async () => ({ currentlyReading: mockBooks }),
+    });
+
+    render(<CurrentlyReading />);
+
+    await waitFor(() => {
+      expect(screen.getByText("Reading (2)")).toBeInTheDocument();
+      expect(screen.getByText("Book 1")).toBeInTheDocument();
+      expect(screen.getByText("Book 2")).toBeInTheDocument();
+    });
+  });
+});

app/__tests__/components/ThemeToggle.test.tsx

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+import React from "react";
+import { render, screen, fireEvent, waitFor } from "@testing-library/react";
+import { ThemeToggle } from "@/app/components/ThemeToggle";
+import { useTheme } from "next-themes";
+
+// Mock next-themes
+jest.mock("next-themes", () => ({
+  useTheme: jest.fn(),
+}));
+
+describe("ThemeToggle Component", () => {
+  const setThemeMock = jest.fn();
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+    (useTheme as jest.Mock).mockReturnValue({
+      theme: "light",
+      setTheme: setThemeMock,
+    });
+  });
+
+  it("renders a placeholder initially (to avoid hydration mismatch)", () => {
+    const { container } = render(<ThemeToggle />);
+    // Initial render should be the loading div
+    expect(container.firstChild).toHaveClass("w-9 h-9");
+  });
+
+  it("toggles to dark mode when clicked", async () => {
+    render(<ThemeToggle />);
+    
+    // Wait for effect to set mounted=true
+    const button = await screen.findByRole("button", { name: /toggle theme/i });
+    
+    fireEvent.click(button);
+    
+    expect(setThemeMock).toHaveBeenCalledWith("dark");
+  });
+
+  it("toggles to light mode when clicked if currently dark", async () => {
+    (useTheme as jest.Mock).mockReturnValue({
+      theme: "dark",
+      setTheme: setThemeMock,
+    });
+
+    render(<ThemeToggle />);
+    
+    const button = await screen.findByRole("button", { name: /toggle theme/i });
+    
+    fireEvent.click(button);
+    
+    expect(setThemeMock).toHaveBeenCalledWith("light");
+  });
+});