ci: chown build/out before split (container created as root)

.github/workflows/build-iso.yml

@@ -176,6 +176,9 @@ jobs:
       - name: Split ISO into 2GiB chunks
         if: success() && github.ref == 'refs/heads/main'
         run: |
+          # ISO + sidecars created by Fedora container as root. Reclaim
+          # ownership so this step (running as runner user) can write.
+          sudo chown -R "$(id -u):$(id -g)" build/out
           cd build/out
           ISO=$(ls *.iso | head -1)
           [ -n "$ISO" ] || { echo "[ERR] no ISO"; exit 1; }