Model Providers Accessibility

**Motivation**
What problem does this solve? Who runs into it and when?
The problem is Right now, it's only codex and claude code, but we need it to connect to multiple model and api providers, like opencode, nvidia, openrouter, google, local models through LM Studio, etc...

It would truly be the best distributed software that would run across any coding agent & any model provider.

The issue names no files, tests, or entry points; begin by locating how the existing Codex and Claude Code providers are connected. Define the supported provider scope and completion criteria first, since the request lists several possible integrations without specifying one change.

Written by the indexing model from the issue text.