refactor: Replace banner with centered logo

- Removed banner.png
- Added centered logo display in README
- Logo width set to 200px for better visibility

Author: Nonanti

README.md

@@ -4,7 +4,9 @@
 [![.NET](https://img.shields.io/badge/.NET-9.0-512BD4)](https://dotnet.microsoft.com)
 [![License](https://img.shields.io/badge/license-MIT-blue)](LICENSE)
 
-![CodeContext.NET Banner](./assets/banner.png)
+<div align="center">
+  <img src="./assets/logo.png" alt="CodeContext.NET Logo" width="200"/>
+</div>
 
 Ever spent hours explaining your codebase patterns to ChatGPT? Or wished GitHub Copilot understood your team's coding style? **CodeContext.NET** solves that.