Fix Spotify playback issues in Expo/React Native app — introduced during App Store integration

I have a mobile app for a physical card game called Lyric Clear It. The app works alongside a deck of physical cards. Players scan a QR code on a card, the app plays a Spotify music clip and stops at a random cue point, and the Manager (the person holding the phone) sees the song name, artist, and year to judge whether the player guessed correctly. IMPORTANT CONTEXT: The web version of this app worked perfectly during testing. The previous developer's server is no longer accessible so the current state of the web version is unknown. All bugs listed below were introduced when the previous developer attempted to integrate and deploy the app to the Apple App Store. This is a Spotify SDK native integration problem, not a logic or backend problem. The core game logic is solid and proven. Known bugs (introduced during App Store integration): - App freezes or crashes after scanning the QR code - Song sometimes does not play at all - App freezes or crashes when the song reaches its stop point - Random freezes during playback What I have: - A working Expo/React Native codebase with existing screens (splash, login, signup, scanner, play screen) - Design mockups for all screens (PNG files) - A working Flask backend API at lyricclearit-api.up.railway.app - Spotify integration already partially built - A GitHub repository with all the code What the app needs to do (full requirements): 1. Splash screen — already designed 2. Login / Signup / Forgot password screens — already built, may need polish 3. QR code scanner — scans the card and loads the song (no in-app genre selection needed — genre is determined by the physical card deck) 4. Play screen — plays the Spotify clip, stops at a random cue point, then displays song name, artist, and year for the Manager to reveal after the player guesses 5. The Spotify playback must stop at a precise millisecond timestamp pulled from the backend — accuracy is critical to the game experience 6. A clean 'reveal' button the Manager taps to show the song info after the player has guessed 7. A 'next round' button to return to scanning 8. Full end-to-end test of the QR scan → Spotify playback → stop → reveal flow on both web and native What the app does NOT need: - In-app scoring (points are tracked with physical cards) - Leaderboards - Lyrics display - Multiplayer/online features - Genre selection screen (physical card decks handle this) Tech stack: - Expo / React Native - TypeScript - Flask backend API - Spotify Web API + Spotify Remote SDK Deliverables: - All known native playback bugs fixed and stable on both iOS and Android - Web version confirmed working - Full QR scan → playback → stop → reveal flow tested and working on both platforms - Precise millisecond playback stopping verified and working - Polished, working app that matches the provided design mockups - Builds for both iOS and Android via EAS Build - Clean code I can hand to another developer in the future Please only apply if you have specific experience with Spotify SDK integration in native iOS/Android apps and have solved Spotify playback issues in React Native before. Share examples of relevant work. Budget: Fixed price preferred. Please quote your rate.