use Claude Code via Nvim and ACP

I forked https://github.com/yetone/avante.nvim and have been adding some additional features for claude-code (acp mode) into it.

I've found it to be the best workflow for me: I'm still editor first, but get the full power of an agent-based workflow.

Makes it easier and more natural to review changes in full-context.

s/o to the folks at Zed for making ACP happen. It's exactly the missing piece for this.