Add a skill around analyzing the existing codebase to determine local practices

[tayloramurphy]

Having a skill that can pull out some info around how code is written / managed in the project repo would be helpful. While we will ship "best practices" in these skills, we want to work w/in context of the codebase the skill was invoked.

Maybe this is updates to AGENTS.md, but perhaps we have another file around this too.

[kaxil]

Do we need that, though? System prompts for Claude generally include checking and using the existing patterns in current code base

[tayloramurphy]

@kaxil my thinking here is that it might make users more comfortable if they had a quick way to output a "style guide" of sorts for their codebase. I did something similar to create a writing guide for my personal writing style to help Claude generate text similar to what I would do. I can do some more exploration on it, but wanted to log the idea