Add backend unit test framework and modularize settings UI

Introduced a Vitest-based backend unit testing framework with supporting scripts, helpers, and GitHub Actions integration. Refactored the admin settings page to a modular architecture, splitting monolithic logic into feature-specific tabs and hooks for improved maintainability and testability. Updated documentation to reflect the new testing setup and settings architecture, and added new dependencies for testing utilities.

tests/api/auth-admin-login.routes.test.ts

@@ -0,0 +1,148 @@
+/**
+ * Component: Admin Login API Route Tests
+ * Documentation: documentation/backend/services/auth.md
+ */
+
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { createPrismaMock } from '../helpers/prisma';
+
+const prismaMock = createPrismaMock();
+const bcryptMock = {
+  compare: vi.fn(),
+};
+const encryptionMock = {
+  decrypt: vi.fn(),
+};
+const tokenMock = {
+  generateAccessToken: vi.fn(() => 'access-token'),
+  generateRefreshToken: vi.fn(() => 'refresh-token'),
+};
+
+vi.mock('@/lib/db', () => ({
+  prisma: prismaMock,
+}));
+
+vi.mock('bcrypt', () => ({
+  default: bcryptMock,
+  ...bcryptMock,
+}));
+
+vi.mock('@/lib/services/encryption.service', () => ({
+  getEncryptionService: () => encryptionMock,
+}));
+
+vi.mock('@/lib/utils/jwt', () => ({
+  generateAccessToken: tokenMock.generateAccessToken,
+  generateRefreshToken: tokenMock.generateRefreshToken,
+}));
+
+const makeRequest = (body: Record<string, any>) => ({
+  json: vi.fn().mockResolvedValue(body),
+});
+
+describe('Admin login route', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    delete process.env.DISABLE_LOCAL_LOGIN;
+  });
+
+  it('blocks local login when disabled', async () => {
+    process.env.DISABLE_LOCAL_LOGIN = 'true';
+    const { POST } = await import('@/app/api/auth/admin/login/route');
+
+    const response = await POST(makeRequest({ username: 'admin', password: 'pass' }) as any);
+    const payload = await response.json();
+
+    expect(response.status).toBe(403);
+    expect(payload.error).toBe('Local login is disabled');
+  });
+
+  it('rejects missing credentials', async () => {
+    const { POST } = await import('@/app/api/auth/admin/login/route');
+
+    const response = await POST(makeRequest({ username: 'admin' }) as any);
+    const payload = await response.json();
+
+    expect(response.status).toBe(400);
+    expect(payload.error).toBe('ValidationError');
+  });
+
+  it('rejects unknown user', async () => {
+    prismaMock.user.findUnique.mockResolvedValue(null);
+    const { POST } = await import('@/app/api/auth/admin/login/route');
+
+    const response = await POST(makeRequest({ username: 'admin', password: 'pass' }) as any);
+    const payload = await response.json();
+
+    expect(response.status).toBe(401);
+    expect(payload.error).toBe('AuthenticationError');
+  });
+
+  it('rejects invalid password', async () => {
+    prismaMock.user.findUnique.mockResolvedValue({
+      id: 'user-1',
+      plexId: 'local-admin',
+      plexUsername: 'admin',
+      plexEmail: null,
+      role: 'admin',
+      avatarUrl: null,
+      authToken: 'enc-hash',
+    });
+    encryptionMock.decrypt.mockReturnValue('hash');
+    bcryptMock.compare.mockResolvedValue(false);
+    const { POST } = await import('@/app/api/auth/admin/login/route');
+
+    const response = await POST(makeRequest({ username: 'admin', password: 'wrong' }) as any);
+    const payload = await response.json();
+
+    expect(response.status).toBe(401);
+    expect(payload.error).toBe('AuthenticationError');
+  });
+
+  it('rejects when password verification throws', async () => {
+    prismaMock.user.findUnique.mockResolvedValue({
+      id: 'user-2',
+      plexId: 'local-admin',
+      plexUsername: 'admin',
+      plexEmail: null,
+      role: 'admin',
+      avatarUrl: null,
+      authToken: 'enc-hash',
+    });
+    encryptionMock.decrypt.mockImplementation(() => {
+      throw new Error('decrypt failed');
+    });
+    const { POST } = await import('@/app/api/auth/admin/login/route');
+
+    const response = await POST(makeRequest({ username: 'admin', password: 'pass' }) as any);
+    const payload = await response.json();
+
+    expect(response.status).toBe(401);
+    expect(payload.error).toBe('AuthenticationError');
+  });
+
+  it('returns tokens for valid credentials', async () => {
+    prismaMock.user.findUnique.mockResolvedValue({
+      id: 'user-3',
+      plexId: 'local-admin',
+      plexUsername: 'admin',
+      plexEmail: 'admin@example.com',
+      role: 'admin',
+      avatarUrl: null,
+      authToken: 'enc-hash',
+    });
+    prismaMock.user.update.mockResolvedValue({});
+    encryptionMock.decrypt.mockReturnValue('hash');
+    bcryptMock.compare.mockResolvedValue(true);
+    const { POST } = await import('@/app/api/auth/admin/login/route');
+
+    const response = await POST(makeRequest({ username: 'admin', password: 'pass' }) as any);
+    const payload = await response.json();
+
+    expect(response.status).toBe(200);
+    expect(payload.success).toBe(true);
+    expect(payload.accessToken).toBe('access-token');
+    expect(payload.refreshToken).toBe('refresh-token');
+    expect(prismaMock.user.update).toHaveBeenCalled();
+  });
+});