create
Creates and returns a production-ready GrantManager instance.
Return
A fully configured GrantManager.
Parameters
context
The platform-specific context (required on Android, ignored on iOS).
store
The storage implementation for tracking request history. When null (the default), the platform default is used: a persistent SharedPreferencesGrantStore on Android (so request history survives process death — see Issue #55) and InMemoryGrantStore on iOS.