fix: use GH-RN- prefix for react-native issues instead of GH-FA-

FA (first 2 chars of 'facebook') was confusing. RN (React Native) is clearer.
Updated both fetch_data.py and existing dataset in-place.

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

Author: Jaspreet Singh