Move speaker reboot bookkeeping into the migration

Keep hardware setup limited to installing the firmware package. The migration owns the pending-reboot marker and preserves prompts for every user migrating before reboot.

install/hardware/dell-xps13-ptl-speaker-firmware.sh

@@ -1,7 +1,3 @@
 if omarchy-hw-dell-xps13-dx13260-ptl; then
-  if omarchy-pkg-missing linux-firmware-cirrus-dx13260; then
-    firmware_pending="/run/omarchy/xps13-ptl-speaker-firmware"
-    sudo install -Dm644 /dev/null "$firmware_pending"
-  fi
   omarchy-pkg-add linux-firmware-cirrus-dx13260
 fi