build: add Dockerfile for api

build/package/api/Dockerfile

@@ -0,0 +1,26 @@
+FROM --platform=${BUILDPLATFORM} golang:1.23-alpine3.20 AS builder
+
+ARG BUILDPLATFORM
+
+WORKDIR /build
+
+COPY go.mod go.sum ./
+
+RUN go mod download
+
+COPY . .
+
+ARG TARGETOS
+ARG TARGETARCH
+
+RUN CGO_ENABLED=0 GOOS=$TARGETOS GOARCH=$TARGETARCH go build -o /build/backoffice-api ./cmd/api
+
+FROM alpine:3.20 AS runtime
+
+WORKDIR /srv
+
+RUN apk add --no-cache ca-certificates
+
+COPY --from=builder /build/backoffice-api /app/backoffice-api
+
+CMD ["/srv/backoffice-api"]