feat(examples): Add Http example and update Enums source generator demo

[senrecep]

Summary

New Examples.Http project added to the examples/ directory; Examples.Enums updated to showcase the StringEnum source generator output.

Changes

Examples.Http — New project

End-to-end demo:

• HttpClientResultExtensions usage (GET, POST, DELETE)
• Fluent request building with HttpRequestBuilder
• Polly retry policy with resilience integration
• Sample IResultErrorMapper implementation

Examples.Enums — Updated (+130 lines)

Demonstrates all aspects of the StringEnumGenerator-generated API:

[StringEnum]
public enum DeliveryStatus { Pending, Shipped, Delivered, Returned }

// Showcased usages:
status.ToSnakeCase()      // "in_progress"
status.ToKebabCase()      // "in-progress"
DeliveryStatusExtensions.TryParse("Shipped", out var s)
DeliveryStatusExtensions.GetNames()
DeliveryStatusExtensions.GetValues()

Related Commit

4c46d8d feat(examples): add Http example project and update Enums source generator demo