APEX-Studio-OSS/Flow — reverse-engineered prompt

Build me a modern Android app called Flow for everyday personal expense tracking. I want it to feel clean and polished, with a simple mobile first interface where someone can add expenses with amount, category, payment method, date, and a short description. It should also let people set category budgets, write finance notes or reminders, and review their spending with easy to understand charts and summaries.

The big thing is privacy. Everything should work locally on the device with no account, no hosted backend, no cloud sync, and no analytics. Users should be able to export all their data to a plain JSON backup file and import it back later. Please keep the scope focused on regular personal money tracking only, not banking connections, investing, taxes, or financial advice.

Make sure it can be packaged and run as an Android app, and include the basics to verify it builds cleanly. If anything is unclear, check the current docs online and keep the implementation aligned with the existing project.