feat: upgrade Node.js version to 20-alpine in Dockerfiles and improve healthcheck command

web/client/Dockerfile

@@ -1,5 +1,5 @@
 # Stage 1: Build the React app
-FROM node:18-alpine AS build
+FROM node:20-alpine AS build
 
 WORKDIR /app
 

web/server/Dockerfile

@@ -1,9 +1,10 @@
 # Node.js backend
-FROM node:18-alpine
+FROM node:20-alpine
 
 # Build tools needed for better-sqlite3 native compilation
 # su-exec for dropping privileges in entrypoint
-RUN apk add --no-cache python3 make g++ su-exec
+# libstdc++ is kept at runtime (needed by better-sqlite3 native addon)
+RUN apk add --no-cache python3 make g++ su-exec libstdc++
 
 WORKDIR /app
 
@@ -12,6 +13,7 @@ COPY package*.json ./
 RUN npm install --omit=dev
 
 # Remove build tools after install to keep image small
+# libstdc++ and su-exec are kept for runtime
 RUN apk del python3 make g++
 
 COPY . .
@@ -26,8 +28,8 @@ RUN chmod +x /usr/local/bin/docker-entrypoint.sh
 
 EXPOSE 3001
 
-HEALTHCHECK --interval=10s --timeout=5s --start-period=30s --retries=3 \
-  CMD wget -qO /dev/null http://localhost:3001/api/health || exit 1
+HEALTHCHECK --interval=10s --timeout=5s --start-period=15s --retries=3 \
+  CMD node -e "require('http').get('http://127.0.0.1:3001/api/health', r => { process.exit(r.statusCode === 200 ? 0 : 1) }).on('error', () => process.exit(1))"
 
 ENTRYPOINT ["docker-entrypoint.sh"]
 CMD ["node", "server.js"]