Bug: Returning from a thread view doesn't show the previous scroll state.

Description:

When viewing a message thread and then returning to the main chat using the top-left back arrow, the message list jumps to very old/top messages instead of returning to the previous position in the main conversation.

Steps to reproduce:

1. Open EmbeddedChat in a channel with enough history to scroll.
2. Scroll in the main chat away from the latest messages.
3. Open a message thread from any message.
4. Click the top-left back arrow to close the thread and return to main chat.

Expected behavior:

Returning from thread view should restore the previous main-chat scroll position (or at least keep the user near where they were before opening the thread), without jumping to old/top messages.

Actual behavior:

After closing the thread, the main chat shows very old messages near the top of history instead of the previous position. In some cases, this also triggers loading older messages immediately.

https://github.com/user-attachments/assets/ff4bb1b3-7f28-4742-bbae-908289a2a522

Start by reproducing the issue in EmbeddedChat with a scrolled conversation, then inspect the thread view and top-left back navigation where the main chat is restored. Done means returning from a thread preserves the previous main-conversation scroll position without jumping to old messages or immediately loading older history.