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

apps/mobile_app/ios/Podfile

@@ -5,9 +5,15 @@ platform :ios, '13.4'
 ENV['COCOAPODS_DISABLE_STATS'] = 'true'
 
 project 'Runner', {
-  'Debug' => :debug,
-  'Profile' => :release,
-  'Release' => :release,
+  'Debug-development' => :debug,
+  'Debug-staging' => :debug,
+  'Debug-production' => :debug,
+  'Profile-development' => :release,
+  'Profile-staging' => :release,
+  'Profile-production' => :release,
+  'Release-development' => :release,
+  'Release-staging' => :release,
+  'Release-production' => :release,
 }
 
 def flutter_root