fix: point README image URL to master branch

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: yadaniyil

README.md

@@ -7,7 +7,7 @@
 Build the beautiful settings screen UI in one moment with `Settings UI for Flutter`
 
 <p align="center">  
-  <img src="https://raw.githubusercontent.com/yako-dev/flutter-settings-ui/dev/assets/v2/settings_ui_cover.png" height="700px">  
+  <img src="https://raw.githubusercontent.com/yako-dev/flutter-settings-ui/master/assets/v2/settings_ui_cover.png" height="700px">  
 </p>  
 
 <br>