fix(leaderboard-service): 删除 Dockerfile 中的 test stage

问题：Dockerfile 中的 test stage 放在最后，导致 docker build 默认使用
test stage 而不是 production stage。容器启动时运行 npm test 而不是
node dist/src/main.js。

修复：删除 test stage，只保留 builder 和 production stages。

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

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

backend/services/leaderboard-service/Dockerfile

@@ -49,27 +49,3 @@ EXPOSE 3000
 
 # Start the application
 CMD ["node", "dist/src/main.js"]
-
-# Test stage
-FROM node:20-alpine AS test
-
-WORKDIR /app
-
-# Install OpenSSL for Prisma
-RUN apk add --no-cache openssl
-
-# Copy package files
-COPY package*.json ./
-COPY prisma ./prisma/
-
-# Install all dependencies (including devDependencies)
-RUN npm ci
-
-# Generate Prisma client (dummy DATABASE_URL for build time only)
-RUN DATABASE_URL="postgresql://user:pass@localhost:5432/db" npx prisma generate
-
-# Copy source code
-COPY . .
-
-# Default command for tests
-CMD ["npm", "test"]