Fix environment manager follow-up compile errors

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

codex-rs/core/src/session/handlers.rs

@@ -519,8 +519,8 @@ pub async fn list_skills(sess: &Session, sub_id: String, cwds: Vec<PathBuf>, for
     let plugins_manager = &sess.services.plugins_manager;
     let fs = sess
         .services
-        .environment
-        .as_ref()
+        .environment_manager
+        .default_environment()
         .map(|environment| environment.get_filesystem());
     let config = sess.get_config().await;
     let codex_home = sess.codex_home().await;

codex-rs/core/src/session/mod.rs

@@ -513,7 +513,7 @@ impl Codex {
         }
 
         let user_instructions = AgentsMdManager::new(&config)
-            .user_instructions(Some(environment.as_ref()))
+            .user_instructions(environment.as_deref())
             .await;
 
         let exec_policy = if crate::guardian::is_guardian_reviewer_source(&session_source) {

codex-rs/core/src/session/tests.rs

@@ -2855,8 +2855,8 @@ async fn new_default_turn_uses_config_aware_skills_for_role_overrides() {
 
     let skill_fs = session
         .services
-        .environment
-        .as_ref()
+        .environment_manager
+        .default_environment()
         .map(|environment| environment.get_filesystem())
         .unwrap_or_else(|| std::sync::Arc::clone(&codex_exec_server::LOCAL_FS));
     let parent_outcome = session