feat: Implement initial authentication, multi-environment support, and core app infrastructure.

lib/features/auth/data/models/register_request.dart

@@ -0,0 +1,18 @@
+import 'package:freezed_annotation/freezed_annotation.dart';
+
+part 'register_request.freezed.dart';
+part 'register_request.g.dart';
+
+@freezed
+abstract class RegisterRequest with _$RegisterRequest {
+  const factory RegisterRequest({
+    required String email,
+    required String password,
+    required String role,
+    String? firstName,
+    String? lastName,
+  }) = _RegisterRequest;
+
+  factory RegisterRequest.fromJson(Map<String, dynamic> json) =>
+      _$RegisterRequestFromJson(json);
+}