fix(ci): lowercase Docker image name in CI workflow and optimize Dockerfile layer creation

.github/workflows/ci.yml

@@ -45,6 +45,9 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
+      - name: Lowercase image name
+        run: echo "IMAGE_NAME=ghcr.io/$(echo "${{ github.repository }}" | tr '[:upper:]' '[:lower:]')" >> "$GITHUB_ENV"
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
 
@@ -55,7 +58,7 @@ jobs:
         id: meta
         uses: docker/metadata-action@v5
         with:
-          images: ghcr.io/${{ github.repository }}
+          images: ${{ env.IMAGE_NAME }}
           flavor: |
             latest=auto
           tags: |