v1.0.0 of coordinator_input

Coordinate input widget for Flutter with geographic and UTM modes, current location support, and testable MVVM architecture. Changelog excerpt: - Published the first stable release of coordinator_input. - Added synchronized geographic and UTM editing with public CoordsInput. - Added support for initializing and emitting values in both geographic and UTM modes. - Added onValueChangedto expose the currently selected representation without breaking onChanged. - Added current-location loading with persisted last-known accuracy feedback. - Added package-level documentation, inline API docs, MIT license, and a pub.dev-ready example.