fix: correct badge URLs from httpdss/struct to httpdss/structkit (#128)

## Summary

Fixes four badge URLs in the README that were pointing to
`httpdss/struct` (the old repo name) instead of `httpdss/structkit`:

- codecov badge link target
- GitHub issues badge
- GitHub pull requests badge  
- GitHub stars badge

## Why

The badges were showing incorrect data (or broken links) because the
repo was previously named `struct` and has since been renamed to
`structkit`. This is a cosmetic but visible bug — anyone landing on the
README would see star/issue counts from the wrong repo.

Part of the open-source marketing strategy ([DEV-9](/DEV/issues/DEV-9)).

Co-authored-by: Paperclip <noreply@paperclip.ing>

Author: httpdss

README.md

@@ -2,10 +2,10 @@
 
 ![StructKit Logo](./docs/assets/github-hero.gif)
 
-[![codecov](https://codecov.io/github/httpdss/structkit/graph/badge.svg?token=JL5WIO1C9T)](https://codecov.io/github/httpdss/struct)
-![GitHub issues](https://img.shields.io/github/issues/httpdss/struct)
-![GitHub pull requests](https://img.shields.io/github/issues-pr/httpdss/struct)
-![GitHub stars](https://img.shields.io/github/stars/httpdss/struct?style=social)
+[![codecov](https://codecov.io/github/httpdss/structkit/graph/badge.svg?token=JL5WIO1C9T)](https://codecov.io/github/httpdss/structkit)
+![GitHub issues](https://img.shields.io/github/issues/httpdss/structkit)
+![GitHub pull requests](https://img.shields.io/github/issues-pr/httpdss/structkit)
+![GitHub stars](https://img.shields.io/github/stars/httpdss/structkit?style=social)
 
 **StructKit** is a powerful, flexible tool for automating project structure creation through YAML configurations. Generate consistent project layouts, boilerplate code, and configurations with template variables, remote content fetching, and intelligent file handling.