implemented chat archive

app/lib/features/chat_archive/domain/entities/chat_entity.dart

@@ -0,0 +1,23 @@
+class ChatEntity {
+  static final _namePattern = RegExp(r"^(.*?) - (.*?)\.md$");
+
+  final String fileName;
+
+  final String? name;
+  final DateTime? dateTime;
+
+  ChatEntity._(this.fileName, {this.name, this.dateTime});
+
+  factory ChatEntity.fromFileName(String fileName) {
+    final match = _namePattern.firstMatch(fileName);
+
+    return ChatEntity._(
+      fileName,
+      name: match?.group(1),
+      dateTime: (match != null) ? DateTime.tryParse(match.group(2)!) : null,
+    );
+  }
+
+  @override
+  String toString() => name ?? fileName;
+}