Implemented basic structure

lib/data/dao/group_dao.dart

@@ -0,0 +1,42 @@
+import 'package:drift/drift.dart';
+import 'package:game_tracker/data/db/database.dart';
+import 'package:game_tracker/data/db/tables/group_table.dart';
+import 'package:game_tracker/data/dto/group.dart';
+
+part 'group_dao.g.dart';
+
+@DriftAccessor(tables: [GroupTable])
+class GroupDao extends DatabaseAccessor<AppDatabase> with _$GroupDaoMixin {
+  GroupDao(super.db);
+
+  Future<List<Group>> getAllGroups() async {
+    final query = select(groupTable);
+    final result = await query.get();
+    return result
+        .map((row) => Group(id: row.id, name: row.name, members: []))
+        .toList();
+  }
+
+  Future<Group> getGroupById(String id) async {
+    final query = select(groupTable)..where((g) => g.id.equals(id));
+    final result = await query.getSingle();
+
+    // todo: Get group members
+
+    return Group(id: result.id, name: result.name, members: []);
+  }
+
+  Future<void> addGroup(String id, String name) async {
+    await into(group).insert(GroupCompanion.insert(id: id, name: name));
+  }
+
+  Future<void> deleteGroup(String id) async {
+    await (delete(group)..where((g) => g.id.equals(id))).go();
+  }
+
+  Future<void> updateGroupname(String id, String newName) async {
+    await (update(group)..where((g) => g.id.equals(id))).write(
+      GroupCompanion(name: Value(newName)),
+    );
+  }
+}