feat: use shell policy in shell snapshot (#11759)

Honor `shell_environment_policy.set` even after a shell snapshot

codex-rs/core/src/tasks/user_shell.rs

@@ -119,6 +119,7 @@ pub(crate) async fn execute_user_shell_command(
         &display_command,
         session_shell.as_ref(),
         turn_context.cwd.as_path(),
+        &turn_context.shell_environment_policy.r#set,
     );
 
     let call_id = Uuid::new_v4().to_string();