refactor: make nanuqsaurus module-based; keep btrfs install profile

scripts/hm-bootstrap.sh

@@ -2,9 +2,12 @@
 set -euo pipefail
 
 UID="$(id -u)"
+USER_NAME="$(id -un)"
 USER_BUS="/run/user/$UID/bus"
 HM_DIR="$HOME/.config/home-manager"
 SKEL_DIR="/etc/skel/.config/home-manager"
+EXPECTED_USER="${NANUQSAURUS_ADMIN_USER:-}"
+HM_TARGET="${NANUQSAURUS_HM_TARGET:-$USER_NAME}"
 
 # Ensure basic PATH for user units
 export PATH="/run/current-system/sw/bin:${PATH:-}"
@@ -79,6 +82,10 @@ trap 'notify "Bootstrap finished" "Your system is fully hydrated. It is recommen
 
 # ---- Home Manager bootstrap -------------------------------------------------
 
+if [[ -n "$EXPECTED_USER" && "$USER_NAME" != "$EXPECTED_USER" ]]; then
+  exit 0
+fi
+
 mkdir -p "$HM_DIR"
 
 for f in flake.nix home.nix; do
@@ -88,5 +95,5 @@ for f in flake.nix home.nix; do
   install -m 600 "$src" "$dst"
 done
 
-home-manager switch --flake "$HM_DIR#admin"
+home-manager switch --flake "$HM_DIR#$HM_TARGET"
 touch "$HM_DIR/.hm_bootstrap_done"

scripts/install-btrfs.sh

@@ -2,7 +2,7 @@
 set -euo pipefail
 
 # Non-interactive Btrfs installer using disko-install.
-# Defaults: DISK=/dev/vda TARGET_HOST=nanuqsaurus
+# Defaults: DISK=/dev/vda TARGET_HOST=nanuqsaurus-btrfs
 # If FLAKE is unset and /etc/nixos/flake.nix exists, it uses /etc/nixos.
 # Otherwise, set FLAKE to a flake URI like:
 #   - git+https://codeberg.org/<owner>/<repo>.git