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>

pkgs/nomarchy-control-center/nomarchy-control-center.sh

@@ -66,8 +66,10 @@ function main_menu() {
                 if [ -z "$gens" ]; then
                     echo "No Home Manager generations found."
                 else
-                    printf "%s\n" "$gens" | awk '{ printf "Desktop gen %s — %s %s%s\n", $5, $1, $2, (NR==1 ? " (current)" : "") }' > /tmp/nomarchy-gens
-                    sel=$(gum choose < /tmp/nomarchy-gens || true)
+                    tmp=$(mktemp)
+                    printf "%s\n" "$gens" | awk '{ printf "Desktop gen %s — %s %s%s\n", $5, $1, $2, (NR==1 ? " (current)" : "") }' > "$tmp"
+                    sel=$(gum choose < "$tmp" || true)
+                    rm -f "$tmp"
                     if [ -n "$sel" ]; then
                         num=${sel#Desktop gen }
                         num=${num%% *}