Gate plugin usage instructions by model capability (#36792)

## What changed

- Add `include_plugin_usage_instructions` to model metadata, defaulting to false.
- Emit generic plugin guidance only when plugins are available and the selected model enables it.
- Enable the capability for interactive model presets while leaving `codex-auto-review` opted out.

GitOrigin-RevId: 67f5a97e978033f5f1d533956c0b9deeae610283

codex-rs/models-manager/src/model_info.rs

@@ -154,6 +154,7 @@ pub fn model_info_from_slug(slug: &str) -> ModelInfo {
         upgrade: None,
         model_messages: Some(local_model_messages_for_slug(slug)),
         include_skills_usage_instructions: false,
+        include_plugin_usage_instructions: false,
         supports_reasoning_summary_parameter: true,
         default_reasoning_summary: ReasoningSummary::Auto,
         support_verbosity: false,