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

backend/backend.Tests/UnitTest1.cs

@@ -0,0 +1,10 @@
+namespace backend.Tests;
+
+public class UnitTest1
+{
+    [Fact]
+    public void Test1()
+    {
+
+    }
+}