Bake GeForce NOW native Linux app (beta) via first-boot installer

NVIDIA's client ships from their own flatpak repo (com.nvidia.geforcenow),
which default-flatpaks can't add alongside Flathub — so a stamped oneshot
service installs it on first boot with retries. Docs note the BC-250 has
no hardware video decode: streams are CPU-decoded, keep to 1080p.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

files/console/usr/lib/systemd/system/bc250-gfn-install.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Install GeForce NOW flatpak (NVIDIA repo, first boot)
+Wants=network-online.target
+After=network-online.target flatpak-add-fedora-repos.service
+ConditionPathExists=!/var/lib/bc250/.gfn-installed
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/bc250-gfn-install
+TimeoutStartSec=45min
+
+[Install]
+WantedBy=multi-user.target