Scroll to a better position after ignoring a user

### Your use case

#### What would you like to do?
When ignoring a user, their messages get hidden. The timeline offset from bottom does not change, so you then end up (much) earlier in tl history than you were previously.

You're likely to experience this if you scroll up to a spammy post (potentially long!), click on the avatar to find the user, and ignore.

#### Why would you like to do it?
stay at the same point in tl

#### How would you like to achieve it?
recalculate offset

### Have you considered any alternatives?

_No response_

### Additional context

_No response_