fix: use vfs storage driver for podman-in-container builds

Runner ignores --privileged, so overlay mounts fail inside the
container. Switch to vfs storage driver via containers config.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -31,11 +31,12 @@ jobs:
   build:
     needs: [test, secrets]
     runs-on: linux
-    container:
-      image: quay.io/podman/stable
-      options: --privileged
+    container: quay.io/podman/stable
     steps:
-      - run: dnf install -y git
+      - run: |
+          dnf install -y git
+          mkdir -p ~/.config/containers
+          printf '[storage]\ndriver = "vfs"\n' > ~/.config/containers/storage.conf
       - run: |
           git clone --depth 1 \
             -c "http.extraHeader=Authorization: token ${{ github.token }}" \