fix: 多阶段构建强制dist层缓存失效

Dockerfile.frontend

@@ -1,20 +1,20 @@
 # Frontend: Node.js static file server with API proxy
-FROM nfqlt/node20
+FROM nfqlt/node20 AS builder
 
-ARG BUILD_TIME
+ARG VERSION
+
+# Copy dist to a versioned path — VERSION changes = different path = cache miss
+COPY dist/ /tmp/dist-v${VERSION}/
+
+FROM nfqlt/node20
 
 WORKDIR /app
 
-# Use BUILD_TIME to invalidate cache so dist/ is always fresh
-RUN echo "Build: $BUILD_TIME"
+# Copy from the versioned path (never cached because path changes with VERSION)
+COPY --from=builder /tmp/dist-v${VERSION}/ /app/dist/
 
-# Copy static files
-COPY dist/ /app/dist/
-
-# Copy server script
 COPY server.js /app/server.js
 
-# Create uploads directory
 RUN mkdir -p /app/uploads && chmod 777 /app/uploads
 
 EXPOSE 80