ci: add gitea workflow for image publish and digest pin

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

@@ -0,0 +1,82 @@
+name: Publish nx-webmail Image (Gitea)
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "nx-webmail/**"
+      - ".gitea/workflows/publish-nx-webmail-image.yml"
+  workflow_dispatch:
+
+jobs:
+  publish:
+    if: ${{ !contains(gitea.actor, '[bot]') }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - 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: ${{ secrets.GHCR_USERNAME }}
+          password: ${{ secrets.GHCR_TOKEN }}
+
+      - name: Read app version
+        id: meta
+        shell: bash
+        run: |
+          version=$(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 }}
+            ${{ steps.meta.outputs.image }}:latest
+
+      - name: Pin digest in docker-compose
+        shell: bash
+        run: |
+          digest="${{ steps.build.outputs.digest }}"
+          if [ -z "$digest" ]; then
+            echo "No digest returned by build step" >&2
+            exit 1
+          fi
+          pinned="    image: ${{ steps.meta.outputs.image }}:${{ steps.meta.outputs.version }}@${digest}"
+          sed -i -E "s|^    image: .*|$pinned|" nx-webmail/docker-compose.yml
+
+      - name: Commit digest pin
+        shell: bash
+        run: |
+          if git diff --quiet -- nx-webmail/docker-compose.yml; then
+            echo "No docker-compose digest changes to commit."
+            exit 0
+          fi
+          git config user.name "gitea-actions[bot]"
+          git config user.email "gitea-actions@local"
+          git remote set-url origin "https://${{ secrets.GITEA_USERNAME }}:${{ secrets.GITEA_TOKEN }}@git.weektab.org/${{ gitea.repository }}.git"
+          git add nx-webmail/docker-compose.yml
+          git commit -m "nx-webmail: pin image digest [skip ci]"
+          git push origin HEAD:main