Add multi-stage Dockerfile and .dockerignore

Dockerfile

@@ -0,0 +1,32 @@
+# ============================================================
+# Stage 1: Build
+# ============================================================
+FROM golang:1.24-alpine AS builder
+
+WORKDIR /build
+
+# 依赖缓存层（变更少，利用 Docker 缓存加速）
+COPY go.mod go.sum ./
+RUN go mod download
+
+# 编译
+COPY . .
+RUN CGO_ENABLED=0 go build -ldflags="-s -w" -o api-server .
+
+# ============================================================
+# Stage 2: Runtime
+# ============================================================
+FROM alpine:3.21
+
+RUN apk add --no-cache ca-certificates tzdata
+
+WORKDIR /app
+
+COPY --from=builder /build/api-server .
+
+# ip2region.xdb 运行时数据目录（卷挂载或 COPY）
+RUN mkdir -p /app/data
+
+EXPOSE 8080
+
+ENTRYPOINT ["./api-server", "serve"]