Cross-Platform App with Authentication

I need a clean, secure mobile application that ships at the same time on iOS and Android. The first milestone is all about a rock-solid user authentication flow—sign-up, log-in, log-out, password reset, and token refresh—built with industry-standard practices (JWT or OAuth). Feel free to use React Native, Flutter, Swift/Kotlin twins, or another modern stack as long as performance is close to native on both platforms.

Because this is the foundation for a bigger roadmap, write modular, well-commented code and structure the project so later additions such as push notifications or in-app purchases can drop in without refactors. Design should follow each platform’s guidelines; no heavy UI work yet, but basic screens must be polished and responsive.

Deliverables
• Compilable source code in a Git repository with clear build steps
• TestFlight-ready iOS build (.ipa) and Google Play Internal release (.aab)
• Brief documentation explaining authentication flow, environment variables, and steps for store submission

Acceptance Criteria
• App installs and runs on the two latest major OS versions for both platforms without crashes
• New users can register, verify email, sign in/out, and recover passwords successfully
• Codebase passes linting and unit tests for all auth components