[codex] trace tools build latency (#28782)

Add more tracing spans around tool building.

codex-rs/login/src/auth/manager.rs

@@ -17,6 +17,7 @@ use std::sync::atomic::AtomicU64;
 use std::sync::atomic::Ordering;
 use tokio::sync::Semaphore;
 use tokio::sync::watch;
+use tracing::instrument;
 
 use codex_agent_identity::ChatGptEnvironment;
 use codex_agent_identity::decode_agent_identity_jwt;
@@ -1719,6 +1720,7 @@ impl AuthManager {
     /// Current cached auth (clone). May be `None` if not logged in or load failed.
     /// For managed ChatGPT auth that needs a proactive refresh, first performs
     /// a guarded reload and then refreshes only if the on-disk auth is unchanged.
+    #[instrument(level = "trace", skip_all)]
     pub async fn auth(&self) -> Option<CodexAuth> {
         if let Some(auth) = self.resolve_external_api_key_auth().await {
             return Some(auth);