fix(leaderboard-service): 修复 Dockerfile 使用 Debian slim 解决 Prisma 兼容性问题

- Builder 阶段从 node:20-alpine 改为 node:20-slim
- 解决 Alpine Linux 上 @prisma/engines 下载失败问题 (ECONNRESET)
- 使用 COPY src ./src 替代 COPY . . 优化构建
- 添加构建输出验证步骤

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/services/leaderboard-service/Dockerfile

@@ -1,13 +1,21 @@
-# Multi-stage build for production
-FROM node:20-alpine AS builder
+# =============================================================================
+# Leaderboard Service Dockerfile
+# =============================================================================
+
+# Build stage - use Debian slim for better Prisma compatibility
+FROM node:20-slim AS builder
 
 WORKDIR /app
 
 # Install OpenSSL for Prisma
-RUN apk add --no-cache openssl
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    openssl \
+    && rm -rf /var/lib/apt/lists/*
 
 # Copy package files
 COPY package*.json ./
+COPY tsconfig*.json ./
+COPY nest-cli.json ./
 COPY prisma ./prisma/
 
 # Install dependencies
@@ -17,11 +25,14 @@ RUN npm ci
 RUN DATABASE_URL="postgresql://user:pass@localhost:5432/db" npx prisma generate
 
 # Copy source code
-COPY . .
+COPY src ./src
 
 # Build the application
 RUN npm run build
 
+# Verify build output exists
+RUN ls -la dist/src/ && test -f dist/src/main.js
+
 # Production stage - use Debian slim for OpenSSL compatibility
 FROM node:20-slim AS production