Add text element metadata to types (#9235)

Initial type tweaking PR to make the diff of
https://github.com/openai/codex/pull/9116 smaller

This should not change any behavior, just adds some fields to types

codex-rs/tui/src/chatwidget/tests.rs

@@ -143,6 +143,8 @@ async fn resumed_initial_messages_render_history() {
             EventMsg::UserMessage(UserMessageEvent {
                 message: "hello from user".to_string(),
                 images: None,
+                text_elements: Vec::new(),
+                local_images: Vec::new(),
             }),
             EventMsg::AgentMessage(AgentMessageEvent {
                 message: "assistant reply".to_string(),