feat: (very) experimental AI DevOps assistant

[edvald]

This expands on #7294 in several ways:

1. The assistant is now conversational. You can ask it for specific things you'd like help with.
2. It's now a multi-agent system with a planner (which you generally give prompts to), a task router, a project explorer, and currently four different expert agents: Kubernetes, Garden, Terraform and Docker.
3. After running a project exploration (informed by the user prompt), the planner creates a list of tasks based on the user prompt(s), runs them by the user, and then proceeds to delegate the tasks in sequence to the experts.
4. All the experts can use some level of improvement, probably especially the Garden one since it's least known to the general model, but I'm fairly pleased so far.
5. This is set up in the Garden Core code for the moment, but I could well imagine this living more server-side.
6. The limitation of needing an Anthropic API key still remains. It would be nice to also support OpenAI at least, but I haven't prioritized that.
7. The system uses LangChain and LangGraph, but I'll note that a lot of custom coding was needed around that.

Kapture.2025-06-04.at.22.54.08.mp4

For the moment the older util ai-config-gen command is still in there, but we might want to just drop that, pending reviews.