Add OpenCode provider integration and strict model selection

docs/api/agents.md

@@ -123,6 +123,18 @@ GET /api/companies/{companyId}/org
 
 Returns the full organizational tree for the company.
 
+## List Adapter Models
+
+```
+GET /api/companies/{companyId}/adapters/{adapterType}/models
+```
+
+Returns selectable models for an adapter type.
+
+- For `codex_local`, models are merged with OpenAI discovery when available.
+- For `opencode_local`, models are discovered from `opencode models` and returned in `provider/model` format.
+- `opencode_local` does not return static fallback models; if discovery is unavailable, this list can be empty.
+
 ## Config Revisions
 
 ```