Plain values are stored verbatim; secrets are
AES-GCM-encrypted at rest and never echoed back. Names use
POSIX shell convention (uppercase letters, digits,
underscore; must start with a letter or _).
Lifecycle hooks (post-create / post-start commands), dotfiles,
git identity, agent config seed, and per-session resource caps
live here. Wired up in
#191
and
#194.