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/tui/src/multi_agents.rs

@@ -183,6 +183,7 @@ pub(crate) fn spawn_end(
         new_agent_role,
         prompt,
         status: _,
+        ..
     } = ev;
 
     let title = match new_thread_id {
@@ -601,6 +602,8 @@ mod tests {
                 new_agent_nickname: Some("Robie".to_string()),
                 new_agent_role: Some("explorer".to_string()),
                 prompt: "Compute 11! and reply with just the integer result.".to_string(),
+                model: "gpt-5".to_string(),
+                reasoning_effort: ReasoningEffortConfig::High,
                 status: AgentStatus::PendingInit,
             },
             Some(&SpawnRequestSummary {
@@ -737,6 +740,8 @@ mod tests {
                 new_agent_nickname: Some("Robie".to_string()),
                 new_agent_role: Some("explorer".to_string()),
                 prompt: String::new(),
+                model: "gpt-5".to_string(),
+                reasoning_effort: ReasoningEffortConfig::High,
                 status: AgentStatus::PendingInit,
             },
             Some(&SpawnRequestSummary {