To play it safe, let's keep `CONFIG_DIR` out of the default list of writable roots. This also fixes an issue where `execWithSeatbelt()` was modifying `writableRoots` instead of creating a new array. --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/openai/codex/pull/419). * #423 * #420 * __->__ #419