Migrate from Replit infrastructure: Neon→PostgreSQL, GCS→S3, ReplitAuth→email/password, add Dockerfile

Dockerfile

@@ -0,0 +1,17 @@
+# Multi-stage build
+FROM node:20-alpine AS builder
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci
+COPY . .
+RUN npm run build
+
+FROM node:20-alpine
+WORKDIR /app
+ENV NODE_ENV=production
+COPY package*.json ./
+RUN npm ci --omit=dev && npm cache clean --force
+COPY --from=builder /app/dist ./dist
+COPY --from=builder /app/client/dist ./client/dist 2>/dev/null || true
+EXPOSE 5000
+CMD ["npm", "run", "start"]