feat(ai): add ADR-036 unified OCR architecture and frontend test coverage

- Add ADR-036 unified OCR architecture (typhoon-ocr via Ollama)
- Extend AI execution profiles for OCR sandbox configuration
- Add comprehensive frontend test coverage (components, hooks, services)
- Add backend test coverage for document-numbering services
- Update OCR sidecar with typhoon-ocr integration
- Add AI policy service and execution profile management
- Update AGENTS.md and architecture documentation

frontend/components/layout/__tests__/theme-toggle.test.tsx

@@ -0,0 +1,58 @@
+// File: frontend/components/layout/__tests__/theme-toggle.test.tsx
+// Change Log:
+// - 2026-06-13: Initial creation - test coverage for ThemeToggle component
+
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { render, screen, fireEvent } from '@testing-library/react';
+import { ThemeToggle } from '../theme-toggle';
+
+const mockSetTheme = vi.fn();
+let mockResolvedTheme = 'dark';
+
+vi.mock('next-themes', () => ({
+  useTheme: () => ({
+    resolvedTheme: mockResolvedTheme,
+    setTheme: mockSetTheme,
+  }),
+}));
+
+describe('ThemeToggle', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    mockResolvedTheme = 'dark';
+  });
+
+  it('ควรแสดงปุ่ม Toggle White/Dark mode', () => {
+    render(<ThemeToggle />);
+    const button = screen.getByTitle('Toggle white/dark mode');
+    expect(button).toBeInTheDocument();
+  });
+
+  it('ควรแสดงข้อความ White เมื่อ theme ปัจจุบันเป็น dark', () => {
+    mockResolvedTheme = 'dark';
+    render(<ThemeToggle />);
+    expect(screen.getByText('White')).toBeInTheDocument();
+  });
+
+  it('ควรแสดงข้อความ Dark เมื่อ theme ปัจจุบันเป็น light', () => {
+    mockResolvedTheme = 'light';
+    render(<ThemeToggle />);
+    expect(screen.getByText('Dark')).toBeInTheDocument();
+  });
+
+  it('ควรเรียก setTheme("light") เมื่อคลิกขณะ theme เป็น dark', () => {
+    mockResolvedTheme = 'dark';
+    render(<ThemeToggle />);
+    const button = screen.getByTitle('Toggle white/dark mode');
+    fireEvent.click(button);
+    expect(mockSetTheme).toHaveBeenCalledWith('light');
+  });
+
+  it('ควรเรียก setTheme("dark") เมื่อคลิกขณะ theme เป็น light', () => {
+    mockResolvedTheme = 'light';
+    render(<ThemeToggle />);
+    const button = screen.getByTitle('Toggle white/dark mode');
+    fireEvent.click(button);
+    expect(mockSetTheme).toHaveBeenCalledWith('dark');
+  });
+});