Add Docker image building to release workflow

Release workflow now builds and pushes Docker images after creating
the draft release:

- Pulse server image (linux/amd64, linux/arm64)
- Docker agent image (linux/amd64, linux/arm64)
- Pushed to both Docker Hub and GHCR
- Tagged with version and 'latest'

Requires DOCKER_USERNAME and DOCKER_PASSWORD secrets to be configured.

.github/workflows/release.yml

@@ -13,6 +13,8 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      tag: ${{ steps.create_release.outputs.tag }}
 
     steps:
       - name: Checkout repository
@@ -148,3 +150,73 @@ jobs:
           echo "All artifacts have been uploaded and validated."
           echo "checksums.txt matches all uploaded binaries."
           echo ""
+
+  build-docker-images:
+    needs: create-release
+    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 Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Pulse server image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          provenance: false
+          tags: |
+            rcourtman/pulse:latest
+            rcourtman/pulse:${{ needs.create-release.outputs.tag }}
+            ghcr.io/${{ github.repository_owner }}/pulse:latest
+            ghcr.io/${{ github.repository_owner }}/pulse:${{ needs.create-release.outputs.tag }}
+
+      - name: Build and push Docker agent image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ./Dockerfile
+          target: agent_runtime
+          platforms: linux/amd64,linux/arm64
+          push: true
+          provenance: false
+          tags: |
+            rcourtman/pulse-docker-agent:latest
+            rcourtman/pulse-docker-agent:${{ needs.create-release.outputs.tag }}
+            ghcr.io/${{ github.repository_owner }}/pulse-docker-agent:latest
+            ghcr.io/${{ github.repository_owner }}/pulse-docker-agent:${{ needs.create-release.outputs.tag }}
+
+      - name: Output Docker image information
+        run: |
+          echo "✅ Docker images built and pushed successfully!"
+          echo ""
+          echo "Server images:"
+          echo "  - rcourtman/pulse:${{ needs.create-release.outputs.tag }}"
+          echo "  - rcourtman/pulse:latest"
+          echo ""
+          echo "Agent images:"
+          echo "  - rcourtman/pulse-docker-agent:${{ needs.create-release.outputs.tag }}"
+          echo "  - rcourtman/pulse-docker-agent:latest"