Preserve Guardian review evidence across compaction (#41846)

## Why

Context compaction can replace original conversation items that Guardian still needs to review approval-sensitive actions.

## What changed

- Retain a bounded, chronological review history independently of the model's compacted history.
- Keep separate limits for user messages and other transcript items so tool traffic cannot evict user instructions.
- Use the retained evidence for synchronous and asynchronous Guardian transcripts, while resetting it after rollback or history reconstruction.

## Testing

- Cover retention through compaction and eviction, reset behavior after rollback, independent size limits, and asynchronous transcript construction.

GitOrigin-RevId: c5851e992820504fc18de8cfec7f6f9f1b69f316

codex-rs/core/src/session/handlers.rs

@@ -335,16 +335,10 @@ pub async fn thread_rollback(sess: &Arc<Session>, sub_id: String, num_turns: u32
         .collect::<Vec<_>>();
     sess.apply_rollout_reconstruction(turn_context.as_ref(), replay_items.as_slice())
         .await;
-    if sess
-        .services
+    sess.services
         .thread_extension_data
-        .remove::<NodeReplReviewEvidence>()
-        .is_some()
-    {
-        sess.guardian_review_session
-            .invalidate_for_node_repl_evidence()
-            .await;
-    }
+        .remove::<NodeReplReviewEvidence>();
+    sess.guardian_review_session.invalidate().await;
     sess.services
         .agent_control
         .rollout_budget()