Add CI/CD workflow for multi-arch Docker builds to GHCR and Docker Hub

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/docker.yml

@@ -0,0 +1,65 @@
+name: Docker
+
+on:
+  push:
+    branches: [main]
+    tags: ["v*"]
+
+permissions:
+  contents: read
+  packages: write
+
+env:
+  GHCR_IMAGE: ghcr.io/jakejarvis/sofa
+  DOCKERHUB_IMAGE: docker.io/jakejarvis/sofa
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        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: Login to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ vars.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Docker metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            ${{ env.GHCR_IMAGE }}
+            ${{ env.DOCKERHUB_IMAGE }}
+          tags: |
+            type=edge,branch=main
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}},enable=${{ !startsWith(github.ref, 'refs/tags/v0.') }}
+            type=sha,prefix=sha-
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max