fix(packages): install uupd before disabling ublue-os/packages COPR

dnf copr disable rewrites the .repo file to the OS-native chroot URL
(centos-stream-10 → fedora-10-{arch}) even when enable specified
fedora-44-{arch}. The subsequent --enablerepo then tries fedora-10
which 404s.

Fix: install uupd while the repo is still enabled, then disable.

Fixes: builds failing on all 5 variants since 2026-06-15

Assisted-by: Claude Sonnet 4.5 via pi
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Jorge Castro

build_scripts/20-packages.sh

@@ -53,8 +53,8 @@ dnf -y --enablerepo "tailscale-stable" install \
 	tailscale
 
 dnf -y copr enable ublue-os/packages "fedora-44-$(arch)"
+dnf -y install uupd
 dnf -y copr disable ublue-os/packages
-dnf -y --enablerepo copr:copr.fedorainfracloud.org:ublue-os:packages install uupd
 
 dnf -y copr enable che/nerd-fonts "centos-stream-${MAJOR_VERSION_NUMBER}-$(arch)"
 dnf -y copr disable che/nerd-fonts