Install what the default-application roles are curated to

Seeding is deliberately conservative: a role whose preferred applications
are all missing is left alone rather than forced. That is right, and it
is also silent -- so a curated handler nobody installs presents as the
machine quietly going back to deciding defaults by installation order,
which is the problem seeding exists to fix. None of Loupe, Papers,
Decibels, Nautilus, mpv or sushi was declared anywhere.

Preview works, on org.gnome.NautilusPreviewer2 rather than the interface
its bus name suggests, but it opened tiled -- shoving the file manager
aside for something meant to be an overlay -- so it gets a float and
center rule sized to leave the file underneath visible.

xdg-utils and desktop-file-utils were undeclared too; seeding from
link-dotfiles started calling them, and the dependency contract said so.

Claude-Session: https://claude.ai/code/session_01BRvzt4H8XXLPVH5MyYdk9L

setup/packages/desktop-packages

@@ -1,6 +1,8 @@
 adw-gtk3-theme
 akmods
 alsa-plugins-pulseaudio
+decibels
+desktop-file-utils
 dnf-plugins-core
 ffmpeg
 fuse-libs
@@ -25,19 +27,24 @@ lame-devel
 libva-devel
 libva-utils
 libxcrypt-compat
+loupe
 mesa-libGL-devel
 mesa-libGLU
 mesa-libOpenCL
 mokutil
 mozilla-openh264
+nautilus
 nautilus-extensions
 nautilus-python
 nextcloud-client
 openssl-devel
 opus-devel
+papers
 python3-dnf-plugin-versionlock
 rocm-opencl
+sushi
 wine
 wine-core
 wine-mono
 winetricks
+xdg-utils

setup/packages/flatpak-packages

@@ -4,3 +4,4 @@ com.bitwarden.desktop
 app.bluebubbles.BlueBubbles
 org.mozilla.thunderbird_esr
 io.missioncenter.MissionCenter
+io.mpv.Mpv