[Feature]: Add app screenshots to the README

**Description:**

Hi, I’m interested in Flutter and mobile app development, and I found this project useful because it helps people find good first issues.

One small improvement could be adding screenshots of the app interface to the README.

**Suggested additions:**

* Home screen screenshot
* Issue search/results screen screenshot
* Short explanation of the main app flow
* Optional Android/iOS preview section

This would help new contributors understand what the app looks like before setting it up locally.