Include spawn agent model metadata in app-server items (#14410)

- add model and reasoning effort to app-server collab spawn items and
notifications
- regenerate app-server protocol schemas for the new fields

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/tools/handlers/multi_agents.rs

@@ -223,6 +223,8 @@ mod spawn {
                     new_agent_nickname,
                     new_agent_role,
                     prompt,
+                    model: args.model.clone().unwrap_or_default(),
+                    reasoning_effort: args.reasoning_effort.unwrap_or_default(),
                     status,
                 }
                 .into(),