feat: Implement Flutter flavors for dev, stage, and prod environments with corresponding configurations and build scripts.

mobile-apps/apps/krow_staff/lib/main_dev.dart

@@ -0,0 +1,13 @@
+import 'package:flutter/material.dart';
+import 'app_config.dart';
+import 'my_app.dart';
+
+void main() {
+  var configuredApp = AppConfig(
+    environment: Environment.dev,
+    appTitle: 'Krow Staff (Dev)',
+    apiBaseUrl: 'https://dev-api.krow.com',
+  );
+
+  runApp(MyApp(config: configuredApp));
+}