docs: add logo to README

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: shreyas-lyzr

.gitignore

@@ -7,4 +7,3 @@ dist/
 site/
 site-v2/
 .claude/
-gitagent.png

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <img src="gitagent.png" alt="gitagent logo" width="120" />
+</p>
+
 # gitagent
 
 [![npm version](https://img.shields.io/npm/v/@shreyaskapale/gitagent)](https://www.npmjs.com/package/@shreyaskapale/gitagent)