feat(menu,install): #50 one-liners + record #46 V2 install pass

#50: Bluetooth menu row + handler self-gate on `command -v
blueman-manager` (no-op when bluetooth is off, like Printers); Control
Center rollback list /tmp/nomarchy-gens → mktemp; usbutils on the
nomarchy-install PATH (fingerprint lsusb probe); export
nomarchy-doctor/control-center/battery-notify as flake packages.
Verified V0 (flake check) + V1 (packages, installer, HM generation build).

Also records #46: the swap=0 + unattended-LUKS fail-closed contracts
(208b8d4) V2-verified via a headless two-variant install — fail-closed
exits before wipe with the disk blank; swap=0 installs with no @swap
subvol and boots to a themed desktop. Both items removed from NEXT.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/home/rofi.nix

@@ -367,6 +367,10 @@ ${themeRows}
 
       bluetooth)
         # blueman-manager GUI (services.blueman.enable, system-side).
+        # Self-gated in the System menu on the CLI; guard here too in case
+        # it's invoked directly with nomarchy.system.bluetooth.enable=false.
+        command -v blueman-manager >/dev/null 2>&1 \
+          || { notify-send "Bluetooth" "Not available (nomarchy.system.bluetooth off?)."; exit 0; }
         exec blueman-manager ;;
 
       printers)
@@ -755,7 +759,8 @@ ${themeRows}
         choice=$( {
           row "Network${menuHint "network"}"        network-wireless
           row "VPN"            network-vpn
-          row "Bluetooth${menuHint "bluetooth"}"      bluetooth
+          command -v blueman-manager >/dev/null 2>&1 \
+            && row "Bluetooth${menuHint "bluetooth"}"      bluetooth
           [ -e "''${XDG_RUNTIME_DIR:-/run/user/$(id -u)}/pulse/native" ] \
             && row "Audio" audio-volume-high
           row "Display" video-display