- Add default/bash/env-bootstrap to the build-time map and a dedicated
section describing what it sets, who sources it, and the dev-link gate
on the PATH prepend.
- Drop 'bluetooth' from the install/user/all.sh hardware-quirks list
(the per-hardware install script is gone now that the wireplumber
config ships through /etc/skel and bt-agent enables at first-run).
- Add a first-run section listing the post-login steps, including the
new enable-user-units.sh that defers user systemctl enables.