The post-install standalone HM activation kept failing in new ways
(daemon access, git ownership, missing PATH on first boot). Wire HM as
a NixOS module in the generated flake instead, so first-boot dotfiles
are activated by `nixos-install` itself with proper system context. The
standalone `homeConfigurations.<user>` is kept alongside for fast
iteration via `nomarchy-env-update`. Also:
- Drop the chroot HM activation block from the installer entirely.
- Move `nomarchy-env-update` from `features/scripts/utils/` to
`core/system/scripts/` so it ships in `nomarchy-system-scripts` and
exists on a freshly-installed system regardless of HM state.
- Set system-wide git `safe.directory` for /etc/nixos and the
impermanence-relocated /persist/etc/nixos so the user-mode HM run
doesn't trip on the root-owned flake repo.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
