feat: Phase 2 (fragment migration), Phase 3 (testing infrastructure), Phase 4 (CI/CD)

Phase 2: Fragment Migration
- Migrated 42 ingredients to 54 fine-grained fragments
- Replaced %include with %ksappend syntax
- Created organized fragment structure (platform/generic-43, platform/generic-rawhide, shared/)
- Updated generator to use fragment paths
- All 16 manifest variants generate successfully

Phase 3: Testing Infrastructure
- Created containerized test runner (tests/container/)
- Added integration test suite (tests/integration/)
- Created golden master fixtures (tests/fixtures/expected_recipes/)
- 41 tests passing (36 unit + 5 integration)
- 54 fragments, 16 recipes validated

Phase 4: CI/CD Integration
- 5 new workflows: validate-recipes, validate-fragments, test-generation, container-tests, build-iso
- Added validation gates before ISO builds
- Works with existing fedora-runner-image
- Local testing support via act_runner

fragments/shared/desktop/gnome/post-scripts.ks

@@ -0,0 +1,65 @@
+# GNOME desktop post-installation configuration
+
+%post --nochroot --log=/mnt/sysimage/root/gnome-desktop-post.log # Beginning of %post section. Those commands are executed outside the chroot environment
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.media-handling.gschema.override<< EOF
+[org.gnome.desktop.media-handling]
+automount-open=false
+autorun-never=true
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.Terminal.gschema.override<< EOF
+[org.gnome.Terminal.Legacy.Profile]
+font='DejaVu Sans Mono 12'
+use-system-font=false
+auditable-bell=false
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.wm.preferences.gschema.override<< EOF
+[org.gnome.desktop.wm.preferences]
+button-layout=':minimize,maximize,close'
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.a11y.gschema.override<< EOF
+[org.gnome.desktop.a11y]
+always-show-universal-access-status=true
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.interface.gschema.override<< EOF
+[org.gnome.desktop.interface]
+enable-animations=false
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.privacy.gschema.override<< EOF
+[org.gnome.desktop.privacy]
+remove-old-temp-files=true
+remember-recent-file=false
+remember-app-usage=false
+disable-camera=true
+disable-microphone=true
+disable-sound-output=true
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.search-providers.gschema.override<< EOF
+[org.gnome.desktop.search-providers]
+disable-external=true
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.notifications.gschema.override<< EOF
+[org.gnome.desktop.notifications.application]
+enable-sound-alerts=false
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.sound.gschema.override<< EOF
+[org.gnome.desktop.sound]
+event-sounds=false
+EOF
+
+cat >> /mnt/sysimage/usr/share/glib-2.0/schemas/org.gnome.desktop.thumbnailers.gschema.override<< EOF
+[org.gnome.desktop.thumbnailers]
+disable-all=true
+EOF
+
+glib-compile-schemas /mnt/sysimage/usr/share/glib-2.0/schemas/
+
+%end # End of the %post section