Remove flutter chat (#26)

Had to squash merge manually as Forgejo was erroring

lib/widgets/lazy_loading/message_avatar.dart

@@ -0,0 +1,36 @@
+import "package:flutter/material.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/author_controller.dart";
+import "package:nexus/helpers/extensions/better_when.dart";
+import "package:nexus/helpers/extensions/get_localpart.dart";
+import "package:nexus/helpers/extensions/show_user_popover.dart";
+import "package:nexus/models/event.dart";
+import "package:nexus/widgets/avatar_or_hash.dart";
+
+class MessageAvatar extends ConsumerWidget {
+  final Event event;
+  final double height;
+  const MessageAvatar(this.event, {this.height = 24, super.key});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) => ref
+      .watch(AuthorController.provider(event))
+      .betterWhen(
+        data: (membership) => InkWell(
+          onTapUp: (details) {
+            context.showUserPopover(
+              membership,
+              event.sender,
+              globalPosition: details.globalPosition,
+            );
+          },
+          child: AvatarOrHash(
+            membership.avatarUrl,
+            membership.displayName ?? event.sender.localpart,
+            height: height,
+          ),
+        ),
+        loading: () =>
+            AvatarOrHash(null, event.sender.localpart, height: height),
+      );
+}