* feat(mobile): align theme foundation with Sure tokens
Generate typed Flutter token constants from the canonical Sure token JSON and route the app through shared light/dark ThemeData construction. This keeps the first mobile design-system step scoped to foundation wiring and regression tests without restyling screens directly.
* fix(mobile): define Sure error container colors
Populate the manual Flutter ColorScheme error container pair from Sure tokens so validation and connection banners keep visible icon/text contrast. Add theme assertions for both light and dark modes.
* fix(mobile): preserve full-width action buttons
