Combines calver date and short commit hash into a single tag
rather than two separate tags.

Assisted-by: Claude Opus 4.6 via Claude Code

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3827e80..c39ac84 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -32,13 +32,14 @@ jobs:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
+      - id: short-sha
+        run: echo "sha=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
       - uses: docker/metadata-action@v5
         id: meta
         with:
           images: ghcr.io/${{ github.repository }}
           tags: |
-            type=raw,value={{date 'YYYYMMDD'}}
-            type=sha,format=short
+            type=raw,value={{date 'YYYYMMDD'}}-${{ steps.short-sha.outputs.sha }}
       - uses: docker/build-push-action@v6
         with:
           context: .