fix(ci): extract binary from Docker image instead of building with Go

.gitea/workflows/release-image.yml

@@ -84,11 +84,10 @@ jobs:
       - name: Build binary
         run: |
           set -eu
-          cd backend
+          # Extract binary from the already-built image (no Go toolchain needed)
-          CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build \
+          docker create --name extract_tmp "$IMAGE_NAME:$VERSION"
-            -ldflags "-s -w -X main.Version=${VERSION} -X main.Commit=${COMMIT} -X main.BuildDate=${BUILD_DATE}" \
+          docker cp extract_tmp:/app/sub2api /tmp/sub2api
-            -o /tmp/sub2api \
+          docker rm extract_tmp
-            ./cmd/server
           cd /tmp
           tar -czf "sub2api_linux_amd64.tar.gz" sub2api
           sha256sum "sub2api_linux_amd64.tar.gz" > checksums.txt