Add 3 apps (AmalanKu, HadisKu, and FastiQuran) from flagodna.com

[cas8398]

Description

This PR adds 3 Islamic applications developed by flagodna.com to the Flutter section:

• AmalanKu: A mobile app specifically designed to help Muslims self-reflect, maintain consistency, and manage daily religious practices.
• HadisKu: Hadith collection app featuring 14 imams' books (Android, Windows, Linux, Web).
• FastiQuran: Free · No Ads · Cross-Platform Quran app (Android, Windows, Linux, Web).

Changes

• Added three new Flutter applications to the list
• All apps are cross-platform and available on multiple devices
• Each entry includes Play Store link and brief description

Checklist

• [x] I've checked that these apps are built with Flutter
• [x] All links are working correctly
• [x] Descriptions are clear and informative

[choubari]

Thanks for your submission, @cas8398. As you may have noticed from the repository, it gathers resources for Muslim developers, and most of the links are open-source projects. Therefore, it’s better to submit GitHub links along with demo links (Google Play, etc.).