docs: increase screenshot size to 600px

Co-Authored-By: Claude (glm-4.7) <noreply@anthropic.com>

Author: smilexth

README.md

@@ -22,7 +22,7 @@
 
   [Features](#-features) • [Install](#-installation) • [Config](#-configuration) • [Usage](#-usage)
 
-  <img src="emon.png" width="300" alt="emon-tui screenshot">
+  <img src="emon.png" width="600" alt="emon-tui screenshot">
 
 </div>