Load notification record and render contextual data

Use a FutureProvider.family keyed on the notification ID so the provider is automatically scoped and disposed with the route. Avoid using StateNotifier for a pure load-once read; FutureProvider.family is simpler and sufficient. The LabelledDataRow widget should accept a nullable String value and render '—' when null — centralising this logic prevents scattered null checks across the screen. Format dates using the intl package's DateFormat with the device locale; do not hardcode locale strings.

Trigger explanation text copy should live in the ARB localisation file, keyed by scenario type enum value, so it is translatable. Apply design tokens for all colours and spacing — do not use hardcoded hex values. Ensure the Riverpod provider ref.watch call is inside the build method, not initState, to correctly respond to provider state changes.

Write flutter_test widget tests covering: (1) loading state renders CircularProgressIndicator; (2) success state with full data renders scenario type label, trigger text, and all three contextual rows with correct formatted values; (3) success state with null contextual fields renders '—' placeholders without exceptions; (4) error state renders error message and retry button; (5) provider is called once on mount and not re-called on hot rebuild. Use mockito or mocktail to mock scenario-notification-repository. Verify contrast compliance using Flutter's SemanticsNode tree in widget tests where possible. No integration tests required at this subtask level — covered in task-012.