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/live/post/base.ks

@@ -0,0 +1,53 @@
+# Live core post-installation configuration
+
+%post --log=/mnt/sysimage/root/live-core-post.log # Beginning of the post-installation section. Add logging.
+
+# Enable livesys services
+systemctl enable livesys.service
+systemctl enable livesys-late.service
+
+# enable tmpfs for /tmp
+systemctl enable tmp.mount
+
+# make it so that we don't do writing to the overlay for things which
+# are just tmpdirs/caches
+# note https://bugzilla.redhat.com/show_bug.cgi?id=1135475
+cat >> /etc/fstab << EOF
+vartmp   /var/tmp    tmpfs   defaults   0  0
+EOF
+
+# work around for poor key import UI in PackageKit
+rm -f /var/lib/rpm/__db*
+echo "Packages within this LiveCD"
+rpm -qa --qf '%{size}\t%{name}-%{version}-%{release}.%{arch}\n' |sort -rn
+# Note that running rpm recreates the rpm db files which aren't needed or wanted
+rm -f /var/lib/rpm/__db*
+
+# go ahead and pre-make the man -k cache (#455968)
+/usr/bin/mandb
+
+# make sure there aren't core files lying around
+rm -f /core*
+
+# remove random seed, the newly installed instance should make it's own
+rm -f /var/lib/systemd/random-seed
+
+# convince readahead not to collect
+# FIXME: for systemd
+
+echo 'File created by kickstart. See systemd-update-done.service(8).' \
+    | tee /etc/.updated >/var/.updated
+
+# Drop the rescue kernel and initramfs, we don't need them on the live media itself.
+# See bug 1317709
+rm -f /boot/*-rescue*
+
+# Disable network service here, as doing it in the services line
+# fails due to RHBZ #1369794
+systemctl disable network
+
+# Remove machine-id on pre generated images
+rm -f /etc/machine-id
+touch /etc/machine-id
+
+%end