Add action for building docker image

.gitea/workflows/build.yaml

@@ -0,0 +1,25 @@
+name: Build and Push Docker Image
+on:
+  push:
+    branches:
+      - main
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Log in to Harbor Registry
+        run: echo "${{ secrets.HARBOR_SECRET }}" | docker login registry.zhbase.ch -u "${{ secrets.HARBOR_USERNAME }}" --password-stdin
+
+      - name: Build Docker Image
+        run: |
+          docker build -t registry.zhbase.ch/zhbase/web:latest .
+
+      - name: Push Docker Image
+        run: |
+          docker push registry.zhbase.ch/zhbase/web:latest
+
+      - name: Log out from Harbor Registry
+        run: docker logout registry.zhbase.ch