fix dockerfile

backend/Dockerfile.server

@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM golang:1.22-alpine as builder
 
 WORKDIR /app
@@ -9,7 +10,10 @@ RUN templ generate
 RUN go get ./...
 RUN go mod tidy
 RUN go mod download
-RUN go build -tags prod -o bin/sac main.go
+
+# Build the Go binary (optimized for production)
+RUN mkdir -p /app/bin
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /app/bin/sac
 
 FROM scratch
 COPY --from=builder /app/bin/sac /sac