feat(search_tool): gate search_tool on model supports_search_tool field (#14502)

codex-rs/core/src/models_manager/model_info.rs

@@ -90,6 +90,7 @@ pub(crate) fn model_info_from_slug(slug: &str) -> ModelInfo {
         input_modalities: default_input_modalities(),
         prefer_websockets: false,
         used_fallback_model_metadata: true, // this is the fallback model metadata
+        supports_search_tool: false,
     }
 }