Refactor rechunking process to use Fedora boot container

Updated the build process to use a privileged Fedora boot container for rechunking.

.github/workflows/build.yml

@@ -91,20 +91,26 @@ jobs:
           labels: ${{ steps.metadata.outputs.labels }}
           oci: true
 
-      # Intelligentes Rechunking auf RPM-Paketbasis mit maximal 128 Layern
+      # Intelligentes Rechunking auf RPM-Paketbasis mit maximal 128 Layern via Container-Lauf
       - name: Apply native bootc rechunking
         id: rechunk
         run: |
           set -x
-          BASE_IMAGE="localhost/${{ env.IMAGE_NAME }}:${{ env.DEFAULT_TAG }}"
           mkdir -p ./chunkah-out
 
-          rpm-ostree compose build-chunked-oci \
-            --bootc \
-            --format-version=2 \
-            --max-layers 128 \
-            --from=$BASE_IMAGE \
-            --output=oci-archive:./chunkah-out/image.ociarchive
+          # Wir starten einen privilegierten Fedora-Bootc-Container, reichen den Podman-Storage
+          # sowie unseren Workspace hinein und führen das Rechunking darin aus.
+          podman run --rm --privileged \
+            -v /var/lib/containers:/var/lib/containers:z \
+            -v .:/workspace:z \
+            -w /workspace \
+            quay.io/fedora/fedora-bootc:stable \
+            rpm-ostree compose build-chunked-oci \
+              --bootc \
+              --format-version=2 \
+              --max-layers 128 \
+              --from=localhost/${{ env.IMAGE_NAME }}:${{ env.DEFAULT_TAG }} \
+              --output=oci-archive:./chunkah-out/image.ociarchive
 
       - name: Login to GitHub Container Registry
         uses: docker/login-action@4907a6ddec9925e35a0a9e82d7399ccc52663121 # v3