Remove flutter chat (#26)

Had to squash merge manually as Forgejo was erroring

lib/models/open_graph_data.dart

@@ -0,0 +1,17 @@
+import "package:freezed_annotation/freezed_annotation.dart";
+part "open_graph_data.freezed.dart";
+part "open_graph_data.g.dart";
+
+@freezed
+abstract class OpenGraphData with _$OpenGraphData {
+  const factory OpenGraphData({
+    @JsonKey(name: "og:title") required String? title,
+    @JsonKey(name: "og:description") required String? description,
+    @JsonKey(name: "og:image") required Uri? imageUrl,
+    @JsonKey(name: "og:image:width") required double? width,
+    @JsonKey(name: "og:image:height") required double? height,
+  }) = _OpenGraphData;
+
+  factory OpenGraphData.fromJson(Map<String, dynamic> json) =>
+      _$OpenGraphDataFromJson(json);
+}