Slim-pacakge refactor

[johnnygreco]

Priority Level

High

Task Summary

To better support the microservice, we plan to refactor the codebase into a mini monorepo, following a "slim" subpackage pattern similar to pydantic-ai.

In the end, we want it to be possible to install the config, engine, and interface modules in an à la carte fashion:

• Microservice SDK: only needs config
• Microservice backend: needs config and engine
• Library: needs config, engine, and interface

Technical Details & Implementation Plan

No response

Dependencies

No response