Fix copy keybinds resetting scrollbuffer location

[Ragnoroct]

What do you want to change?

I would like to fix #13026 so ctrl+shift+c does not interact weirdly with kitty protocol and cause the scroll buffer to reset every time the c key is not the first one up.

Why do you want to make this change?

I've had this bug plaguing me for many months. Tried different configuration and pty hacks. Until recently where I went into the code and found where a real Zig fix could be made.

Lots of devs use TUI coding agents. Copying text from responses is also common. Scrolling up to copy something and getting sent down to the bottom each time when you want to copy the next thing is annoying.

I acknowledge that:

• I have read the Contributing Guide and understand the contribution process.
• I have read and agree to follow the AI Usage Policy.
• I wrote this vouch request myself, in my own voice, without AI generating it.

[jcollie]

!vouch

[Ragnoroct]

Thanks! :)