Tencent/MMKV ? reverse-engineered prompt

Build me a small, fast key value storage library for mobile and desktop apps, something like MMKV, where developers can save booleans, numbers, strings, and other simple values without having to think about syncing or manual save calls.

I want it to work smoothly on Android and iOS first, with the same core storage logic shared across platforms, and it should also be able to support macOS, Windows, POSIX, and HarmonyOS if possible. Make it feel easy to use from app startup, with a simple global instance and basic encode and decode calls. It should store data efficiently on disk, handle multiple processes safely when needed, and stay small and fast.

If you need to check the latest platform setup details or build steps, look them up online and use the current docs.