☂️ [ai] add agent pointers to our shared styleguide

[pq]

Our styleguide.md is being used to great effect in Gemini Code Assist reviews but local agents are unaware of it. This task tracks creating "Pointer Files" for specific AI agents so the styleguide can act as a single source of truth for them all.

• [ai] add an .aiconfig file for local gemini agents #8893
• [ai] add Claude config #8912
• cursor?
• codex?

[pq]

Note that I'm open to looking at other approaches too (e.g., skills) but this seems pretty low-lift with a pretty nice payoff. If all the agents are (at least) using the style guide we should get some better initial contributions.

Input welcome!

📟 @jwren @jakemac53