Enable containerization for simplified deployment and scaling of the app

Adds Dockerfile, docker-compose files, and deployment scripts for containerizing the React/Express app.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 3a22ac80-cd1d-4441-9e36-f24fc2f4c3de
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/3478f7c3-db8c-4fca-9165-3adbdf1b5829/e8da43e7-d99c-4328-9fdc-485bdeecffc1.jpg

Dockerfile

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+# Multi-stage build for optimized production image
+FROM node:18-alpine AS builder
+
+# Set working directory
+WORKDIR /app
+
+# Copy package files
+COPY package*.json ./
+
+# Install all dependencies (including devDependencies for build)
+RUN npm ci
+
+# Copy source code
+COPY . .
+
+# Build the application
+RUN npm run build
+
+# Production stage
+FROM node:18-alpine AS production
+
+# Install dumb-init for proper signal handling
+RUN apk add --no-cache dumb-init
+
+# Create non-root user
+RUN addgroup -g 1001 -S nodejs
+RUN adduser -S nodejs -u 1001
+
+# Set working directory
+WORKDIR /app
+
+# Copy package files
+COPY package*.json ./
+
+# Install only production dependencies
+RUN npm ci --only=production && npm cache clean --force
+
+# Copy built application from builder stage
+COPY --from=builder /app/dist ./dist
+COPY --from=builder /app/dist/public ./dist/public
+
+# Create uploads directory for file uploads
+RUN mkdir -p uploads && chown nodejs:nodejs uploads
+
+# Change ownership of app directory
+RUN chown -R nodejs:nodejs /app
+
+# Switch to non-root user
+USER nodejs
+
+# Expose port
+EXPOSE 5000
+
+# Set environment variables
+ENV NODE_ENV=production
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+  CMD node -e "const http = require('http'); const options = { host: 'localhost', port: 5000, path: '/', timeout: 2000 }; const req = http.request(options, (res) => { process.exit(res.statusCode === 200 ? 0 : 1); }); req.on('error', () => process.exit(1)); req.end();"
+
+# Start the application with dumb-init
+CMD ["dumb-init", "npm", "start"]