Add initial project structure and configuration files for iOS and Android

lib/core/errors/exceptions.dart

@@ -0,0 +1,20 @@
+class AppException implements Exception {
+  final String message;
+  
+  AppException(this.message);
+  
+  @override
+  String toString() => message;
+}
+
+class NetworkException extends AppException {
+  NetworkException(super.message);
+}
+
+class AuthException extends AppException {
+  AuthException(super.message);
+}
+
+class UnexpectedException extends AppException {
+  UnexpectedException(super.message);
+}