feature: display buffer navigation

[dlants]

Did you check the docs?

• I have read all the docs

Is your feature request related to a problem? Please describe.

I'd like to set up keybindings and commands to jump around the navigation buffer, something like:

[e / ]e go to previous / next error
[t / ]t go to previous / next tool use
[m / ]m go to previous/next message header

Describe the solution you'd like

We should annotate the nodes of interest during rendering, so when we create a mounted node, we have a list of locations and their rendered coordinates. Then it's just a question of figuring out where the current cursor is, and where the next/previous positions are.

Describe alternatives you've considered

na

Additional context

No response