Autogenerated thread title shows <@userid> for @mentions

Reproduction steps

In a channel you have thread creation permissions in, send a message that includes an @mention early on
Long press the message you just sent
Tap 'Create thread'

Expected behaviour

The automatically generated thread title should include the @mention text. e.g. if I create a thread off a message that starts with @Fullest, the autogenerated thread title should start with @Fullest or whatever my nickname is in that community at the time

Actual behaviour

The automatically generated thread title shows the user id. e.g. if I create a thread off a message that starts with @Fullest, the autogenerated thread title starts with <@1471663952882754315> Note: this is the exact same bug as 4162, but applied to mobile

Build information

Version 2026.10.100, Beta 15, Channel Beta, Build 2866, Android 16 (arm64), Device Google Pixel 9a, Locale en-US, Push fcm, Flutter 3.47.9, Dart 3.13.7

Platform

Android, iOS