ci: Create preview Docker build workflow

.github/workflows/build-docker-dev.yml

@@ -0,0 +1,48 @@
+# https://github.com/wukko/cobalt/blob/current/.github/workflows/docker.yml
+
+name: Build Development Docker image
+on:
+  push:
+  workflow_dispatch:
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+jobs:
+  build-and-push-image:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Log in to the Container registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Get release metadata
+        id: release-meta
+        run: |
+          echo "commit_short=$(git rev-parse --short HEAD)" >> $GITHUB_OUTPUT
+          echo "branch=$(git rev-parse --abbrev-ref HEAD | sed 's/\//-/g')" >> $GITHUB_OUTPUT
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          tags: |
+            type=raw,value=${{ steps.release-meta.outputs.branch }}-${{ steps.release-meta.outputs.commit_short }}
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

.github/workflows/build-docker.yml

@@ -1,6 +1,6 @@
 # https://github.com/wukko/cobalt/blob/current/.github/workflows/docker.yml
 
-name: Build Docker image
+name: Build Release Docker image
 on:
   workflow_dispatch:
 env: