Track client-authored developer messages in rollout history (#38243)

## What changed

- Mark developer messages received from clients with `client_authored` harness
  metadata when `retain_client_developer_messages` is enabled.
- Carry that provenance through pending input and persist it alongside rollout
  response items without adding it to provider requests or the serialized
  `TurnInput` payload.
- Preserve existing behavior for unannotated response items and when the
  feature is disabled.

## Testing

- Cover client item injection before and during turns, additional application
  context, rollout replay, image resize notices, and serialization boundaries.

GitOrigin-RevId: f385c177732becde732272e4b8440eb91f5c1039

codex-rs/ext/goal/src/runtime.rs

@@ -404,7 +404,7 @@ impl GoalRuntimeHandle {
         let item = continuation_steering_item(&protocol_goal_from_state(goal));
 
         if let Err(err) = thread
-            .try_start_turn_if_idle(vec![TurnInput::ResponseItem(item)])
+            .try_start_turn_if_idle(vec![TurnInput::ResponseItem(item.into())])
             .await
         {
             let reason = err.reason();