claude refactorings, flutter best practices, platform dependent changes, general cleanup

lib/api/holidays/get_holidays.dart

@@ -0,0 +1,16 @@
+import 'dart:convert';
+import 'package:http/http.dart' as http;
+
+import 'get_holidays_response.dart';
+
+class GetHolidays {
+  Future<GetHolidaysResponse> query() async {
+    var response = (await http.get(Uri.parse('https://ferien-api.de/api/v1/holidays/HE'))).body;
+    var data = jsonDecode(response) as List<dynamic>;
+    return GetHolidaysResponse(
+        List<GetHolidaysResponseObject>.from(
+            data.map<GetHolidaysResponseObject>((e) => GetHolidaysResponseObject.fromJson(e as Map<String, dynamic>))
+        )
+    );
+  }
+}