Scaffold a feature module

Stands up one navigable feature the same way every time — a fixed lib/features/<feature>/presentation/ folder (dumb View + one 1:1 Notifier/AsyncNotifier ViewModel + widgets/ + scoped <feature>_providers.dart), downward-only dependencies with no cross-feature imports, reactive reads as scoped StreamProviders over a repository .watch(), every mutation through one repository single-write-path method, typed Result/Failure surfaced as AsyncValue, a typed go_router route carrying identity in path params, ARB parity across locales, family+autoDispose keying, and EdgeInsetsDirectional-only geometry. Use when adding a screen, tab, or feature folder; wiring a feature Notifier/View…