younusrahman/SRCalculator — reverse-engineered prompt

I want a simple cross platform calculator app called SRCalculator that works on Android, iPhone, and Windows devices from one shared codebase. Please set up the solution so it builds cleanly and feels like a real finished app, not just a demo.

The app should have a clean calculator screen with large buttons, a display for the current number and result, and the basic math actions people expect, like add, subtract, multiply, divide, clear, delete, decimal input, and equals. Make sure it handles common edge cases gracefully, like dividing by zero, repeated taps, and long numbers. It should be responsive on phones and tablets and feel native enough on each platform.

Please also include sensible project structure, app icons or placeholder branding, and enough comments so someone can follow along later. If anything is outdated, look up current docs online and modernize it while keeping the app simple and easy to maintain.