Renamed IBillingRepository to BillingRepository and updated all references across data, domain, and use case layers for consistency. Improved documentation and comments for repository and use cases. Adjusted typography letter spacing in design system and made minor UI tweaks to the spending breakdown card.
Introduces the client billing feature with domain, data, and presentation layers. Adds billing BLoC, navigation, UI widgets, and integrates with mock financial repository. Updates localization files for billing-related strings, adds new icons and typography, and registers url_launcher plugins for Linux, macOS, and Windows platforms.
