Ship `services.fwupd.enable` distro-wide (mkDefault) for firmware updates
via LVFS — the daemon + metadata-refresh timer only, no automatic
flashing, so applying an update stays an explicit `fwupdmgr update`. A
no-op where LVFS sees no devices; overridable natively. Sits with the
other mkDefault desktop services rather than a nomarchy toggle (it's a
single service, like upower).
Also documents the `nomarchy.system.power.*` options in the README table
(missed when the power module landed) and adds a short note on the
fwupd default.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>