fix: default npm registry mirror for docker build

Dockerfile

@@ -7,7 +7,7 @@ WORKDIR /app
 # 可选：使用哪种包管理器构建（默认 pnpm；也可传 npm）
 ARG PKG_MANAGER=pnpm
 # 可选：镜像加速（例如 https://registry.npmmirror.com）
-ARG NPM_REGISTRY=
+ARG NPM_REGISTRY=https://registry.npmmirror.com
 
 ENV CI=true
 
@@ -19,7 +19,9 @@ RUN if [ -n "$NPM_REGISTRY" ]; then npm config set registry "$NPM_REGISTRY"; fi
 
 RUN set -eux; \
   if [ "$PKG_MANAGER" = "pnpm" ]; then \
-    npm i -g pnpm@9 && pnpm i --frozen-lockfile; \
+    npm i -g pnpm@9; \
+    if [ -n "$NPM_REGISTRY" ]; then pnpm config set registry "$NPM_REGISTRY"; fi; \
+    pnpm i --frozen-lockfile; \
   elif [ "$PKG_MANAGER" = "npm" ]; then \
     npm ci --no-audit --fund=false; \
   else \