`nomarchy-welcome` wrote a "starter" `~/.config/home-manager/home.nix`
for users without one. Two problems:
1. Wrong path. The installer-generated canonical home.nix lives at
`/etc/nixos/home.nix` and is imported via the flake (both
home-manager.users and the standalone homeConfigurations). Nothing
in the installer flow ever reads `~/.config/home-manager/home.nix`
— it's a dead file.
2. Broken content. The starter is missing `home.username`,
`home.homeDirectory`, `home.stateVersion`, and doesn't import
`nomarchy.nixosModules.home`. Even on a hand-migration path it
wouldn't evaluate as a standalone HM config.
So in the installer flow it's dead, and in the migration flow it's
broken. Removed Step 4 entirely. The git-init step (was Step 5) is
now Step 4. Hand-migrated users follow `docs/MIGRATION.md`, which has
the correct home.nix template.
Found during Pillar 8 audit of first-boot UX.
6e0d17b859