The persistence block at core/system/impermanence.nix:75 read
`users.nomarchy = { directories = [...]; }` — the username was a
literal, not a reference. For any user not literally named "nomarchy"
the block was silently inert and ~/.ssh, ~/.gnupg, ~/.local/share/keyrings,
Documents, Downloads, Pictures, Videos, Projects were wiped on every boot.
Adds `nomarchy.system.impermanence.user` (str, default "nomarchy") and
uses it via `users.${cfg.user}`. The installer now writes the chosen
username alongside `enable` and `mainLuksName` so impermanence installs
with non-default usernames are correct out of the box.
docs/OPTIONS.md: fixes the wrong path on the impermanence row
(documented `impermanence.enable`, real option is
`nomarchy.system.impermanence.enable`) and adds entries for
`mainLuksName` and `user`.
Found during Pillar 8 audit of core/system modules.
749f970fb0