Implement simpler provider configuration

[kujtimiihoxha]

Implement a way to add openai compatible APIs without code changes.

Should allow us to add

• Local models
• xAi
• OpenRouter
• Deepseek
• ... Many others

[kujtimiihoxha]

Working on something that allows you to basically configure

{
  "$schema": "./opencode-schema.json",
  "lsp": {
    "gopls": {
      "command": "gopls"
    }
  },
  "agents": {
    "coder": {
      "model": "grok-3-beta",
      "provider": "xai"
    }
  },
  "providers": {
    "xai": {
      "type": "openai",
      "baseUrl": "https://api.x.ai/v1",
      "apiKey": "*******"
    }
  }
}

And it would work

This won't count token expenses because those need to be configured but the configuration allows you to do that too.

I think what I will do is add a bunch of providers out of the box (with pre configured models) but any openai compatible endpoint should be able to be setup using the configuration above