fix(reward-service): 修复 Dockerfile 使用 Debian slim 和正确的 CMD 路径

- Builder 阶段从 node:20-alpine 改为 node:20-slim
- 修复 CMD 路径从 dist/main.js 改为 dist/src/main.js
- 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/reward-service/Dockerfile

@@ -2,11 +2,16 @@
 # Reward Service Dockerfile
 # =============================================================================
 
-# Build stage
-FROM node:20-alpine AS builder
+# Build stage - use Debian slim for better Prisma compatibility
+FROM node:20-slim AS builder
 
 WORKDIR /app
 
+# Install OpenSSL for Prisma
+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 ./
@@ -26,7 +31,7 @@ COPY src ./src
 RUN npm run build
 
 # Verify build output exists
-RUN ls -la dist/ && test -f dist/main.js
+RUN ls -la dist/src/ && test -f dist/src/main.js
 
 # Production stage - use Debian slim for OpenSSL compatibility
 FROM node:20-slim
@@ -67,4 +72,4 @@ HEALTHCHECK --interval=30s --timeout=3s --start-period=40s --retries=3 \
   CMD wget -q --spider http://localhost:3005/health || exit 1
 
 # Start service
-CMD ["node", "dist/main.js"]
+CMD ["node", "dist/src/main.js"]