Add LittleShop.Client SDK library with complete API wrapper

Features:
- Complete .NET client SDK for LittleShop API
- JWT authentication with automatic token management
- Catalog service for products and categories
- Order service with payment creation
- Retry policies using Polly for resilience
- Error handling middleware
- Dependency injection support
- Comprehensive documentation and examples

SDK Components:
- Authentication service with token refresh
- Strongly-typed models for all API responses
- HTTP handlers for retry and error handling
- Extension methods for easy DI registration
- Example console application demonstrating usage

Test Updates:
- Fixed test compilation errors
- Updated test data builders for new models
- Corrected service constructor dependencies
- Fixed enum value changes (PaymentStatus, OrderStatus)

Documentation:
- Complete project README with features and usage
- Client SDK README with detailed examples
- API endpoint documentation
- Security considerations
- Deployment guidelines

Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

LittleShop.Tests/Unit/CategoryServiceTests.cs

@@ -15,7 +15,6 @@ public class CategoryServiceTests : IDisposable
 {
     private readonly LittleShopContext _context;
     private readonly ICategoryService _categoryService;
-    private readonly IMapper _mapper;
 
     public CategoryServiceTests()
     {
@@ -25,15 +24,8 @@ public class CategoryServiceTests : IDisposable
             .Options;
         _context = new LittleShopContext(options);
 
-        // Set up AutoMapper
-        var mappingConfig = new MapperConfiguration(mc =>
-        {
-            mc.AddProfile(new MappingProfile());
-        });
-        _mapper = mappingConfig.CreateMapper();
-
         // Create service
-        _categoryService = new CategoryService(_context, _mapper);
+        _categoryService = new CategoryService(_context);
     }
 
     [Fact]