feat: add gallery feature with database integration and rendering capabilities

lib/services/gallery_db.dart

@@ -0,0 +1,39 @@
+import "package:hive_flutter/hive_flutter.dart";
+import "package:quotegen_client/models/gallery_item.dart";
+
+class GalleryDB {
+
+  static const String _boxName = "gallery";
+
+  static LazyBox<String> get _box => Hive.lazyBox<String>(_boxName);
+
+
+  static Future<void> saveItem(GalleryItem item) async {
+    await _box.put(item.id, item.toJsonString());
+  }
+
+  static Future<void> deleteItem(String id) async {
+    await _box.delete(id);
+  }
+
+  static Future<List<GalleryItem>> getAllItems() async {
+    final keys = _box.keys.toList();
+    final items = <GalleryItem>[];
+
+    for (final key in keys) {
+      final raw = await _box.get(key);
+      if (raw != null) {
+        try {
+          items.add(GalleryItem.fromJsonString(raw));
+        } catch (e) {
+          // skip corrupted entries
+          print("GalleryDB: failed to parse item $key: $e");
+        }
+      }
+    }
+
+    items.sort((a, b) => b.createdAt.compareTo(a.createdAt));
+    return items;
+  }
+
+}