Persist additional tool definitions in rollout history (#50435)

## Why

`additional_tools` response items were excluded from rollout persistence, dropping their tool definitions from saved history.

## What changed

- Persist `additional_tools` items in both legacy and paginated history modes.
- Expose the variant in generated JSON schemas, TypeScript types, and Python models, with an optional `id`, a `role`, and arbitrary JSON tool definitions.

## Testing

Add a recorder round-trip test that verifies tool definitions survive recording and loading in both history modes without parse errors.

GitOrigin-RevId: 0e7c7b1c10401ec6513fb744de642a1cf9e461d7

codex-rs/protocol/src/models.rs

@@ -1010,12 +1010,12 @@ impl InternalChatMessageMetadataPassthrough {
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, JsonSchema, TS)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ResponseItem {
-    #[schemars(skip)]
-    #[ts(skip)]
     AdditionalTools {
         #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[ts(optional)]
         id: Option<ResponseItemId>,
         role: String,
+        #[ts(type = "unknown[]")]
         tools: Vec<serde_json::Value>,
     },
     Message {