chore: add China mirror sources for Go and Alpine

Dockerfile

@@ -1,7 +1,14 @@
-FROM golang:1.21-alpine AS builder
+FROM golang:1.26-alpine AS builder
 
 WORKDIR /app
 
+# 设置 Go 国内镜像源
+RUN go env -w GOPROXY=https://goproxy.cn,direct && \
+    go env -w GOSUMDB=off
+
+# 设置 Alpine 国内镜像源
+RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.tuna.tsinghua.edu.cn/g' /etc/apk/repositories
+
 RUN apk add --no-cache gcc musl-dev
 
 COPY go.mod go.sum ./
@@ -11,7 +18,10 @@ COPY . .
 
 RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o server ./cmd/server
 
-FROM alpine:3.19
+FROM alpine:latest
+
+# 设置 Alpine 国内镜像源
+RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.tuna.tsinghua.edu.cn/g' /etc/apk/repositories
 
 RUN apk --no-cache add ca-certificates