ci: add forgejo workflow to build and push docker image

.forgejo/workflows/docker.yml

@@ -0,0 +1,44 @@
+name: docker
+
+on:
+  push:
+    branches: [main]
+    tags: ['v*']
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: docker
+    container:
+      image: ghcr.io/catthehacker/ubuntu:act-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: docker/setup-buildx-action@v3
+
+      - name: login
+        uses: docker/login-action@v3
+        with:
+          registry: summer.node.femboy.page
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: summer.node.femboy.page/arcanegram/arcanesync-server
+          tags: |
+            type=ref,event=branch
+            type=ref,event=tag
+            type=sha,format=short
+            type=raw,value=latest,enable={{is_default_branch}}
+
+      - uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max