add build yaml for docker image creation

.gitea/workflows/02_build.yaml

@@ -0,0 +1,52 @@
+name: Build image
+on:
+  push:
+    branches:
+      - main
+      - build
+    tags:
+      - v*
+      
+jobs:
+  build:
+    container:
+      image: docker:dind
+      volumes:
+        - /data/.cache/act:/data/.cache/act
+        - /var/lib/docker/image:/var/lib/docker/image
+        - /var/lib/docker/overlay2:/var/lib/docker/overlay2
+    steps:
+      - name: Starting docker daemon
+        run: docker-init -- dockerd --host=unix:///var/run/docker.sock &
+      - name: Installing necessary packages
+        run: apk add nodejs git curl bash
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Docker meta
+        id: meta
+        uses: https://github.com/docker/metadata-action@v4
+        with:
+          # list of Docker images to use as base name for tags
+          images: |
+            git.fai.st/fedi-image-bot/moderation-fe
+          # generate Docker tags based on the following events/attributes
+          tags: |
+            type=raw,value=latest,enable=${{ github.ref == format('refs/heads/{0}', 'main') }}
+            type=ref,event=branch
+            type=semver,pattern={{raw}}
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Login to fai.st docker registry
+        uses: docker/login-action@v2
+        with:
+          registry: git.fai.st
+          username: ${{ secrets.DOCKER_USER }}
+          password: ${{ secrets.DOCKER_PASS }}
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          platforms: linux/amd64,linux/arm64
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}