add new ci file

.gitea/workflows/build_ci.yml

@@ -0,0 +1,26 @@
+name: ci
+
+on:
+  push:
+    branches:
+      - 'main'
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ vars.REGISTRY_DOCKER }}
+          username: ${{ secrets.REGISTRY_DOCKER_USER }}
+          password: ${{ secrets.REGISTRY_DOCKER_PASS }}
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          push: true
+          tags: user/app:latest