nx-webmail: switch Umbrel app to prebuilt GHCR image

.github/workflows/publish-nx-webmail-image.yml

@@ -0,0 +1,69 @@
+name: Publish nx-webmail Image
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+    paths:
+      - "nx-webmail/**"
+      - ".github/workflows/publish-nx-webmail-image.yml"
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  publish:
+    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: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Read app version
+        id: meta
+        shell: bash
+        run: |
+          version=$(grep '^version:' nx-webmail/umbrel-app.yml | awk -F'"' '{print $2}')
+          if [ -z "$version" ]; then
+            echo "Could not read nx-webmail version from umbrel-app.yml" >&2
+            exit 1
+          fi
+          echo "version=$version" >> "$GITHUB_OUTPUT"
+          echo "image=ghcr.io/weektab/nx-webmail" >> "$GITHUB_OUTPUT"
+
+      - name: Build and push image
+        id: build
+        uses: docker/build-push-action@v6
+        with:
+          context: ./nx-webmail
+          file: ./nx-webmail/Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: |
+            ${{ steps.meta.outputs.image }}:${{ steps.meta.outputs.version }}
+            ${{ steps.meta.outputs.image }}:latest
+
+      - name: Summary
+        shell: bash
+        run: |
+          {
+            echo "### nx-webmail image published"
+            echo ""
+            echo "- Image: \`${{ steps.meta.outputs.image }}\`"
+            echo "- Version tag: \`${{ steps.meta.outputs.version }}\`"
+            echo "- Digest: \`${{ steps.build.outputs.digest }}\`"
+          } >> "$GITHUB_STEP_SUMMARY"