refactor: share common files between images; trim fedora-remote for a VM

- Move Kanidm/flatpak/finalize.d/sshd files to images/shared/{files,repos}
  and have build.sh overlay them for every image.
- fedora-remote: aggressive hardware trim (no firmware, no kernel-modules-extra,
  no non-QEMU guest agents), keep + enable qemu-guest-agent (Proxmox).
- Fixes the missing package-list (release step) for fedora-remote.

images/shared/files/finalize.d/50-packages

@@ -0,0 +1,12 @@
+#!/bin/bash
+# Runs in the target root during `rpm-ostree compose image` (edition 2024
+# finalize.d hook). Records the installed package list next to the treefile so
+# build.sh can hand it to release.sh without having to mount the built image.
+set -euo pipefail
+
+if [[ -z "${RPMOSTREE_WORKDIR:-}" ]]; then
+  echo "RPMOSTREE_WORKDIR not set, skipping package list" >&2
+  exit 0
+fi
+
+rpm -qa --root "${PWD}" --qf '%{NAME} %{EVR}\n' | sort > "${RPMOSTREE_WORKDIR}/packages-current.txt"