feat: add multi-environment support (development, staging, production)
- Replace dotenv with compile-time dart-define-from-file config per flavor
- Add Android product flavors with applicationIdSuffix and per-flavor AndroidManifest
- Add iOS build configurations, schemes, per-flavor plists and entitlements
- Configure ProGuard rules for R8 compatibility with Entrust/Antelop SDK
- Restructure assets into shared/ and per-flavor directories
- Generate per-flavor launcher icons for Android and iOS
- Refactor app initialization into initApp() with per-flavor entry points
- Update asset paths across auth, home, profile, splash modules and sf_shared
JulianAlcala
ef0abc2f85