[QoL] Thread Viewer doesn't open to last viewed page.

[aivct]

Expected Behaviour:
In the main ChatGPT proper, you can pick off where you left off.
Ie, if you generated 5 responses, and decided one of the middle responses were best, ChatGPT opens to the same page.
Behaviour:
Thread viewer always opens up to last response. Ie, if your tree is as follows, where the first response is a dead end, the second response is a huge tree, and the third response is also dead end, thread viewer opens up to the third response, every time.
Workarounds:
Flicking < and > to match, although that gets quite annoying.
Solution:
Save currentLeafIndex as well, either that, or have a parallel array called "currentLeafIndices" or something like that.