feat: align shared app foundations

test/common/feedback_email_service_test.dart

@@ -0,0 +1,17 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:jinzhi_flutter_app/features/settings/application/feedback_email_service.dart';
+
+void main() {
+  test('encodes feedback email subject and body as a mailto URI', () {
+    final uri = FeedbackEmailService.composeMailtoUri(
+      recipient: 'support@example.com',
+      subject: '金值反馈',
+      body: '问题描述\n第二行',
+    );
+
+    expect(uri.scheme, 'mailto');
+    expect(uri.path, 'support@example.com');
+    expect(uri.queryParameters['subject'], '金值反馈');
+    expect(uri.queryParameters['body'], '问题描述\n第二行');
+  });
+}