[Feature] Support floating input popup

[kalomak]

So the output pane would stay in the normal split layout, but the input prompt would open in a popup.
Motivation is that i want to see the output/progress on the side but i don't like that the input window
is in the corner of the screen instead of middle when writing prompts.

[sudo-tee]

At the moment the layout is pretty rigid to avoid complexity. I haven't tossed out the idea entirely. But this will require a bit of refactoring before we can implement this. Things like the context bar need to follow the input window.

In the meantime you can always hide the input window with the command 'Opencode toggle_input' . It's not exactly what you want but it may help your workflow.