fix(ci): lowercase GHCR image tag and simplify image name

GHCR requires lowercase repository names. Use repository_owner with
bash lowercase expansion for the container build, and hardcode the
lowercase image name in the integration workflow.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/build-test-container.yml

@@ -12,6 +12,9 @@ permissions:
   contents: read
   packages: write
 
+env:
+  IMAGE: ghcr.io/${{ github.repository_owner }}/psproxmoxve-integration:latest
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -19,6 +22,10 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
+      - name: Lowercase image name
+        id: image
+        run: echo "name=${IMAGE,,}" >> "$GITHUB_OUTPUT"
+
       - name: Log in to GHCR
         uses: docker/login-action@v3
         with:
@@ -32,4 +39,4 @@ jobs:
           context: tests/infrastructure
           file: tests/infrastructure/Dockerfile
           push: true
-          tags: ghcr.io/${{ github.repository }}/integration-test:latest
+          tags: ${{ steps.image.outputs.name }}

.github/workflows/integration-tests.yml

@@ -70,7 +70,7 @@ jobs:
     runs-on: [self-hosted, proxmox, integration]
     timeout-minutes: 45
     container:
-      image: ghcr.io/${{ github.repository }}/integration-test:latest
+      image: ghcr.io/goodolclint/psproxmoxve-integration:latest
       volumes:
         - /opt/pve-isos:/opt/pve-isos
         - /opt/pve-images:/opt/pve-images