Remove flutter chat (#26)

Had to squash merge manually as Forgejo was erroring

lib/models/info/file.dart

@@ -0,0 +1,15 @@
+import "package:freezed_annotation/freezed_annotation.dart";
+part "file.freezed.dart";
+part "file.g.dart";
+
+@freezed
+abstract class FileInfo with _$FileInfo {
+  /// Information for images, [size] is in bytes.
+  const factory FileInfo({
+    @JsonKey(name: "mimetype") String? mimeType,
+    int? size,
+  }) = _FileInfo;
+
+  factory FileInfo.fromJson(Map<String, Object?> json) =>
+      _$FileInfoFromJson(json);
+}