feat: implement scroll-to-bottom on output option

[benodiwal]

Closes #8408

[mitchellh]

Thank you, but I'm not convinced this is the right approach. I suspect that this might slow down our IO throughput noticeably since newlines are common and we have to now add a conditional there. It may not though since the conditional will almost always be the same value.

If you can show benchmarks that may help...

But I still think the best way to do this would be to implement it in the renderer actually and have the frame build check if our final line changed pins at all and if so, to trigger a scroll.

[benodiwal]

Thanks @mitchellh! The renderer approach seems right.

I tried these three implementations:

1. Stream Handler (termio/stream_handler.zig) <- Current commit

• Checks on every \n in linefeed()

2. Renderer - Scrollbar Total (renderer/generic.zig)

• Compares scrollbar.total between frames in updateFrame()

3. Renderer - Pin Tracking (renderer/generic.zig) ← your suggestion

• Checks if final line's pin changed (node pointer or y offset)

I have all three ready on my local. I would like your input on 2 as well. It seems simpler since it reuses existing scrollbar data without adding new fields.

[benodiwal]

I have pushed the changes according to the approach you suggested using Pin Tracking.