chore: add github workflow to release docker images

.github/workflows/tag-server-docker-image.yml

@@ -0,0 +1,39 @@
+name: Tag server Docker image for release
+
+on:
+  release:
+    types: [released]
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository_owner }}/blink-server
+
+jobs:
+  tag-image:
+    runs-on: ${{ github.repository_owner == 'coder' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Log in to the Container registry
+        uses: docker/login-action@5e57cd118135c172c3672efd75eb46360885c0ef # v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
+
+      - name: Tag image as latest and with git tag
+        run: |
+          SHORT_SHA=$(echo "${{ github.event.release.target_commitish }}" | cut -c1-7)
+          SOURCE="${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${SHORT_SHA}"
+          GIT_TAG="${{ github.event.release.tag_name }}"
+
+          echo "Tagging ${SOURCE} as latest and ${GIT_TAG}"
+
+          docker buildx imagetools create \
+            --tag "${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest" \
+            --tag "${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${GIT_TAG}" \
+            "${SOURCE}"