fix: include rollout_path in NewConversationResponse (#3352)

Adding the `rollout_path` to the `NewConversationResponse` makes it so a
client can perform subsequent operations on a `(ConversationId,
PathBuf)` pair. #3353 will introduce support for `ArchiveConversation`.

---
[//]: # (BEGIN SAPLING FOOTER)
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* #3353
* __->__ #3352

codex-rs/core/src/codex.rs

@@ -416,6 +416,7 @@ impl Session {
             error!("failed to initialize rollout recorder: {e:#}");
             anyhow::anyhow!("failed to initialize rollout recorder: {e:#}")
         })?;
+        let rollout_path = rollout_recorder.rollout_path.clone();
         // Create the mutable state for the Session.
         let state = State {
             history: ConversationHistory::new(),
@@ -509,6 +510,7 @@ impl Session {
                 history_log_id,
                 history_entry_count,
                 initial_messages,
+                rollout_path,
             }),
         })
         .chain(post_session_configured_error_events.into_iter());