dev_env: install acl for become_user file copies

When the login user differs from the become_user (ubongo connects as sjat,
the role copies files as claude), Ansible needs ACLs on its temp files;
without the acl package it falls back to an unsupported chmod syntax and
fails. Molecule didn't catch it (root login can chown directly).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

roles/dev_env/defaults/main.yml

@@ -14,6 +14,7 @@ dev_env__packages:
   - tmux
   - git
   - stow
+  - acl              # lets Ansible become_user an unprivileged user (sjat -> claude) for file copies
   - build-essential
   - curl
   - ca-certificates