Convert Finance Web App to Flutter

I already have a browser-based personal finance app written in Vanilla JavaScript (ES6+), HTML5, CSS3 and backed by Supabase. It runs flawlessly on desktop, but now it needs to live on phones and tablets with the same smooth experience users expect from a native app. After weighing React Native and Ionic, I settled on Flutter so that a single codebase can target iOS, Android and still preserve web/PWA continuity without forcing me to rewrite every business rule from scratch.

The mobile build must cover everything the web version does today and layer in the future-facing items listed below:

• User Authentication
• Budget Tracking
• Expense Notifications (push)
• Mobile Invoicing
• AI Voice Assistant
• Investment Portfolio
• Tax Calculator
• Business Analytics
• Client CRM

What I need from you is a clean Flutter project that consumes my existing Supabase backend, applies a fresh modern UI (no need to mimic the current desktop styling), and ships production-ready APK/IPA builds plus a deployable web/PWA target. Source code, build scripts, and concise setup documentation should be part of the hand-off so I can keep iterating beyond this milestone.

If the first release feels as fast and native as the desktop version—handling offline caching, real-time sync, and push notifications seamlessly—the job is done right.