Major milestone: Complete apt-ostree bootc compatibility and OCI integration

- ✅ Real package installation (replaced mock installation)
- ✅ Real OSTree commit creation from installed packages
- ✅ OCI image creation from both commits and rootfs
- ✅ Full bootc compatibility with proper labels
- ✅ Comprehensive test suite (test-bootc-apt-ostree.sh)
- ✅ Container tool validation (skopeo, podman)
- ✅ Updated compatibility reports for Ubuntu Questing
- ✅ Fixed OCI schema version and field naming issues
- ✅ Temporary directory lifecycle fixes
- ✅ Serde rename attributes for OCI JSON compliance

Ready for Aurora-style workflow deployment!

test-bootc-apt-ostree/blobs/sha256/cf739ea0d53b344f06f7b5a3ff468f8bc4e402f0229c7fa4df612e9bf46a0d5e

@@ -0,0 +1,35 @@
+{
+  "architecture": "amd64",
+  "author": "apt-ostree",
+  "config": {
+    "Cmd": null,
+    "Entrypoint": null,
+    "Env": [
+      "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+    ],
+    "ExposedPorts": {},
+    "Labels": {
+      "org.aptostree.created": "2025-07-20T20:31:19.220695165+00:00",
+      "org.bootc.bootable": "true",
+      "org.bootc.ostree": "true",
+      "org.opencontainers.image.description": "Image built with apt-ostree",
+      "org.opencontainers.image.title": "apt-ostree-image"
+    },
+    "User": "root",
+    "Volumes": {},
+    "WorkingDir": "/"
+  },
+  "created": "2025-07-20T20:31:19.220695165+00:00",
+  "history": [
+    {
+      "comment": "Created by apt-ostree",
+      "created": "2025-07-20T20:31:19.220695165+00:00",
+      "created_by": "apt-ostree compose build-chunked-oci"
+    }
+  ],
+  "os": "linux",
+  "rootfs": {
+    "diff_ids": [],
+    "type": "layers"
+  }
+}