Require pull down to refresh rather than automatically refreshing when you scroll back up to the top

**Describe the bug**
I'm on the latest version of dev.phanpy.social. The "auto refresh timeline posts" checkbox is unchecked. This is being the behavior forever but I would like to have to pull down to refresh the toots rather than automatically refreshing when I reach the top of the loaded timeline.

Sometimes I like to scroll down a bit when I first load the app and then scroll back up as I read and when I reach the top I don't get to fully read the top two before it refreshes and pushes it down. I just think having to pull down to refresh explicitly would be a better experience.

**To Reproduce**
Steps to reproduce the behavior:
1. Load the app and scroll down a few tooths so that the top post is off the screen.
2. Scroll back up so that the top post is at the top but you don't intend to refresh the timeline.
3. The timeline will refresh anyway. However many toots have loaded in the meantime will have pushed that top tooth down probably off the screen.

**Expected behavior**
I'd like to be able to scroll back up to the top too without having it automatically refresh, but still allow me to manually pull down to refresh.

**Desktop (please complete the following information):**
- every device, OS, and browser combination I've tried.

No file or test is named in the issue. Reproduce the timeline behavior by scrolling down and back to the top, then trace the timeline refresh entry point; done means returning to the top no longer refreshes automatically while an intentional pull-down still refreshes the timeline.

Written by the indexing model from the issue text.