feature: Integrate with kitty-navigator.nvim

[thisisrandy]

Did you check the docs?

• I have read all the sidekick.nvim docs

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

I've described the issue and outlined a solution in discussion. Basically, sidekick ignores <c-h/j/k/l> by design when the agent window is either floating or positioned at an edge. This breaks kitty-navigator.nvim. I found that with a small modification to kitty-navigator, I can make it successfully navigate from the agent window to both vim splits and terminal splits. However, I must also completely override the sidekick mappings under cli.win.keys with the kitty-navigator mappings to complete the integration.

Describe the solution you'd like

I'm imagining that there might be some way for sidekick to "fall back" to <c-h/j/k/l> mappings set elsewhere, kind of like the way remap works, but I don't currently know how to implement this myself. Would very much appreciate some guidance or an outright fix.

Describe alternatives you've considered

See the description. Modifying kitty-navigator and using its mappings in the sidekick config is a kludge.

Additional context

No response