Use the originating model when recording conversation history (#44243)

## Why

History recording used the model captured at turn start, so switching models within a turn could apply stale image preparation and tool-output truncation rules.

## What changed

Pass explicit model metadata through conversation recording. Record model responses and tool results using their originating step's settings, and capture the current model for pending input recorded during startup interruption or task completion.

## Testing

Add regression coverage for tool results across a model switch, explicit model selection for plain and annotated history, and image input retained during interruption and completion. Extend model-switching tests to verify that prepared media and item identity survive switching back to a multimodal model in live, resumed, and forked threads.

GitOrigin-RevId: 5bc750c30c334acb9b802cb80fdea01daffa84a1

codex-rs/core/src/compact.rs

@@ -791,8 +791,12 @@ async fn drain_to_completed(
         };
         match event {
             Ok(ResponseEvent::OutputItemDone(item)) => {
-                sess.record_conversation_items(turn_context, std::slice::from_ref(&item))
-                    .await;
+                sess.record_conversation_items(
+                    turn_context,
+                    turn_context.model_info(),
+                    std::slice::from_ref(&item),
+                )
+                .await;
             }
             Ok(ResponseEvent::ServerReasoningIncluded(included)) => {
                 sess.set_server_reasoning_included(included).await;