Migrate from Getx to Riverpod/GoRouter/Slang

[Leonavichus]

Current project uses GetX for state management, routing, and localization. Migrate to Riverpod (state/dependency injection), GoRouter (navigation), and Slang (i18n) for better type safety, testability, and maintainability.

[r4khul]

nice, we have to make sure to remove tightly coupled ui & state as much as possible while leveraging riverpod