Add comprehensive test suite infrastructure

- Create backend xUnit test project with Moq and FluentAssertions
- Add test utilities: TestDataFactory, MockHttpContext, TestUserClaims
- Create AuthControllerTests with comprehensive auth scenarios
- Install Jest and React Testing Library for frontend
- Configure jest.config.ts and jest.setup.ts with Next.js support
- Add test scripts to package.json

frontend/jest.config.ts

@@ -0,0 +1,37 @@
+import type { Config } from 'jest';
+import nextJest from 'next/jest.js';
+
+const createJestConfig = nextJest({
+  // Provide the path to your Next.js app to load next.config.js and .env files in your test environment
+  dir: './',
+});
+
+// Add any custom config to be passed to Jest
+const config: Config = {
+  coverageProvider: 'v8',
+  testEnvironment: 'jsdom',
+  setupFilesAfterEnv: ['<rootDir>/jest.setup.ts'],
+  moduleNameMapper: {
+    '^@/(.*)$': '<rootDir>/src/$1',
+  },
+  testPathIgnorePatterns: [
+    '<rootDir>/node_modules/',
+    '<rootDir>/.next/',
+  ],
+  collectCoverageFrom: [
+    'src/**/*.{js,jsx,ts,tsx}',
+    '!src/**/*.d.ts',
+    '!src/**/*.stories.{js,jsx,ts,tsx}',
+  ],
+  coverageThreshold: {
+    global: {
+      branches: 0,
+      functions: 0,
+      lines: 0,
+      statements: 0,
+    },
+  },
+};
+
+// createJestConfig is exported this way to ensure that next/jest can load the Next.js config which is async
+export default createJestConfig(config);