[Bug]: Android: Back from a pull request opened in a thread lands on the PR list instead of the thread #24753

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/mobile

Steps to reproduce

1. On Android, open a thread that has a linked pull request.
2. Open the pull request from the thread (Git controls or the thread's linked PR).
3. Press Back (toolbar or system Back).

Expected behavior

Back returns to the thread the pull request was opened from.

Actual behavior

Back lands on the Pull Requests list. Opening the PR replaces the chat's back stack, so the thread is gone from history and has to be found again.

Impact

Major degradation or frequent failure

Version or commit

Current Android release

Environment

Android app

Notes

Fix in progress: #18839 (contextual PR links preserve the chat history). It is currently conflicting with main and has had no activity since 2026-10-21. iOS behavior is out of scope for that PR.