feat: include "reasoning" messages in Rust TUI (#892)

As shown in the screenshot, we now include reasoning messages from the
model in the TUI under the heading "codex reasoning":


![image](https://github.com/user-attachments/assets/d8eb3dc3-2f9f-4e95-847e-d24b421249a8)

To ensure these are visible by default when using `o4-mini`, this also
changes the default value for `summary` (formerly `generate_summary`,
which is deprecated in favor of `summary` according to the docs) from
unset to `"auto"`.

codex-rs/core/src/rollout.rs

@@ -114,7 +114,7 @@ impl RolloutRecorder {
                 ResponseItem::Message { .. }
                 | ResponseItem::FunctionCall { .. }
                 | ResponseItem::FunctionCallOutput { .. } => {}
-                ResponseItem::Other => {
+                ResponseItem::Reasoning { .. } | ResponseItem::Other => {
                     // These should never be serialized.
                     continue;
                 }