Read receipt support

Fixes #93

lib/models/paginate.dart

@@ -1,6 +1,7 @@
 import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:freezed_annotation/freezed_annotation.dart";
 import "package:nexus/models/event.dart";
+import "package:nexus/models/read_receipt.dart";
 
 part "paginate.freezed.dart";
 part "paginate.g.dart";
@@ -10,6 +11,9 @@ part "paginate.g.dart";
 class const Paginate({
   required final IList<Event> events,
   required final IList<Event> relatedEvents,
+
+  /// Read receipts for the events, by event ID.
+  final IMap<String, IList<ReadReceipt>> receipts = const .empty(),
   required final bool hasMore,
 }) with _$Paginate {
   Map<String, Object?> toJson() => _$PaginateToJson(this);

lib/models/read_receipt.dart

@@ -13,6 +13,11 @@ class const ReadReceipt({
   required final String eventId,
   @EpochDateTimeConverter() required final DateTime timestamp,
 }) with _$ReadReceipt {
+  String get thread => switch (threadId) {
+    final threadId? when threadId.isNotEmpty => threadId,
+    _ => "main",
+  };
+
   Map<String, Object?> toJson() => _$ReadReceiptToJson(this);
 
   factory ReadReceipt.fromJson(Map<String, Object?> json) =>

lib/models/settings.dart

@@ -1,7 +1,7 @@
 import "package:material_ui/material_ui.dart";
 import "package:freezed_annotation/freezed_annotation.dart";
 import "package:nexus/models/room_order.dart";
-import "package:nexus/models/typing_indicators.dart";
+import "package:nexus/models/show_and_send.dart";
 
 part "settings.freezed.dart";
 part "settings.g.dart";
@@ -17,7 +17,11 @@ class const Settings({
   final bool swipeToReply = false,
   final bool hideMembershipEvents = false,
   final RoomOrder roomOrder = .unreadFirst,
-  final TypingIndicators typingIndicators = .showAndSend,
+  final ShowAndSend typingIndicators = .showAndSend,
+
+  /// When not sending, read receipts are still sent privately, so that the
+  /// user's other devices know what has been read.
+  final ShowAndSend readReceipts = .showAndSend,
 }) with _$Settings {
   Map<String, Object?> toJson() => _$SettingsToJson(this);
 

lib/models/show_and_send.dart

@@ -0,0 +1,2 @@
+/// Whether to show something from others, and send it to them, e.g. typing indicators or read receipts.
+enum ShowAndSend { showAndSend, show, neither }

lib/models/typing_indicators.dart

@@ -1 +0,0 @@
-enum TypingIndicators { showAndSend, show, neither }