Respect model support for reasoning summaries (#32290)

## What changed

- Add `supports_reasoning_summary_parameter` to model metadata, defaulting to
  `true` for backward compatibility.
- Omit `reasoning.summary` and its summary-delivery stream option when the
  selected model does not support the parameter.
- Apply the capability of the final selected model when a spawned agent uses a
  different model.

## Testing

- Cover unsupported models in regular requests and spawned-agent model
  overrides.

GitOrigin-RevId: 72b783799fc0685cef1501ef2dbf62d1308ceead

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

@@ -139,6 +139,7 @@ pub fn model_info_from_slug(slug: &str) -> ModelInfo {
         base_instructions: BASE_INSTRUCTIONS.to_string(),
         model_messages: local_personality_messages_for_slug(slug),
         include_skills_usage_instructions: false,
+        supports_reasoning_summary_parameter: true,
         default_reasoning_summary: ReasoningSummary::Auto,
         support_verbosity: false,
         default_verbosity: None,