feat(example): add UI to display related publications

- Export RelatedPublication entity in SDK main library
- Create RelatedPublicationsWidget to display list of related publications
- Create RelatedPublicationItem widget for individual publication items
- Update PublicationDetailContent to show related publications section
- Display related publications with cover image, title, and release date
- Add navigation placeholder for related publication items

Author: ryanaidilp

app/example/lib/features/publications/presentation/widgets/publication_detail_content.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:gap/gap.dart';
 import 'package:stadata_example/core/constants/app_sizes.dart';
 import 'package:stadata_example/core/generated/strings.g.dart';
+import 'package:stadata_example/features/publications/presentation/widgets/related_publications_widget.dart';
 import 'package:stadata_flutter_sdk/stadata_flutter_sdk.dart';
 
 class PublicationDetailContent extends StatelessWidget {
@@ -33,7 +34,17 @@ class PublicationDetailContent extends StatelessWidget {
           if (publication.abstract != null && publication.abstract!.isNotEmpty)
             _buildAbstractSection(context, theme, t),
 
-          const Gap(AppSizes.spaceLg),
+          if (publication.abstract != null && publication.abstract!.isNotEmpty)
+            const Gap(AppSizes.spaceLg),
+
+          // Related publications section
+          if (publication.relatedPublications.isNotEmpty)
+            RelatedPublicationsWidget(
+              relatedPublications: publication.relatedPublications,
+            ),
+
+          if (publication.relatedPublications.isNotEmpty)
+            const Gap(AppSizes.spaceLg),
 
           // Action buttons
           _buildActionButtons(context, theme, t),

app/example/lib/features/publications/presentation/widgets/related_publications_widget.dart

@@ -0,0 +1,159 @@
+import 'package:flutter/material.dart';
+import 'package:gap/gap.dart';
+import 'package:stadata_example/core/constants/app_sizes.dart';
+import 'package:stadata_flutter_sdk/stadata_flutter_sdk.dart';
+
+class RelatedPublicationsWidget extends StatelessWidget {
+  const RelatedPublicationsWidget({
+    required this.relatedPublications,
+    super.key,
+  });
+
+  final List<RelatedPublication> relatedPublications;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(AppSizes.spaceMd),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(
+              'Related Publications',
+              style: theme.textTheme.titleMedium?.copyWith(
+                fontWeight: FontWeight.w600,
+              ),
+            ),
+            const Gap(AppSizes.spaceMd),
+            ListView.separated(
+              shrinkWrap: true,
+              physics: const NeverScrollableScrollPhysics(),
+              itemCount: relatedPublications.length,
+              separatorBuilder:
+                  (context, index) => const Divider(
+                    height: AppSizes.spaceMd,
+                  ),
+              itemBuilder: (context, index) {
+                final related = relatedPublications[index];
+                return RelatedPublicationItem(publication: related);
+              },
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class RelatedPublicationItem extends StatelessWidget {
+  const RelatedPublicationItem({
+    required this.publication,
+    super.key,
+  });
+
+  final RelatedPublication publication;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+
+    return InkWell(
+      onTap: () {
+        // Navigate to the related publication
+        // This could be implemented to open the publication detail
+      },
+      borderRadius: BorderRadius.circular(8),
+      child: Padding(
+        padding: const EdgeInsets.all(AppSizes.spaceXs),
+        child: Row(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            // Cover image
+            ClipRRect(
+              borderRadius: BorderRadius.circular(4),
+              child: SizedBox(
+                width: 60,
+                height: 80,
+                child: Image.network(
+                  publication.cover,
+                  fit: BoxFit.cover,
+                  errorBuilder:
+                      (context, error, stackTrace) => ColoredBox(
+                        color: theme.colorScheme.surfaceContainerLowest,
+                        child: Icon(
+                          Icons.book,
+                          size: 24,
+                          color: theme.colorScheme.onSurfaceVariant,
+                        ),
+                      ),
+                  loadingBuilder: (context, child, loadingProgress) {
+                    if (loadingProgress == null) return child;
+                    return ColoredBox(
+                      color: theme.colorScheme.surfaceContainerLowest,
+                      child: Center(
+                        child: SizedBox(
+                          width: 16,
+                          height: 16,
+                          child: CircularProgressIndicator(
+                            strokeWidth: 2,
+                            value:
+                                loadingProgress.expectedTotalBytes != null
+                                    ? loadingProgress.cumulativeBytesLoaded /
+                                        loadingProgress.expectedTotalBytes!
+                                    : null,
+                          ),
+                        ),
+                      ),
+                    );
+                  },
+                ),
+              ),
+            ),
+
+            const Gap(AppSizes.spaceSm),
+
+            // Publication info
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text(
+                    publication.title,
+                    style: theme.textTheme.bodyMedium?.copyWith(
+                      fontWeight: FontWeight.w500,
+                    ),
+                    maxLines: 2,
+                    overflow: TextOverflow.ellipsis,
+                  ),
+                  const Gap(AppSizes.spaceXs),
+                  Text(
+                    _formatDate(publication.releaseDate),
+                    style: theme.textTheme.bodySmall?.copyWith(
+                      color: theme.colorScheme.onSurfaceVariant,
+                    ),
+                  ),
+                ],
+              ),
+            ),
+
+            // Arrow icon
+            Icon(
+              Icons.arrow_forward_ios,
+              size: 16,
+              color: theme.colorScheme.onSurfaceVariant,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  String _formatDate(DateTime date) {
+    return '${date.day.toString().padLeft(2, '0')}/'
+        '${date.month.toString().padLeft(2, '0')}/'
+        '${date.year}';
+  }
+}

packages/stadata_flutter_sdk/lib/stadata_flutter_sdk.dart

@@ -46,6 +46,7 @@ export 'src/features/features.dart'
         NewsCategory,
         PressRelease,
         Publication,
+        RelatedPublication,
         StaticTable,
         StatisticClassification,
         StrategicIndicator,