feat: Add Dockerfile for Railway deployment

Added production-ready Dockerfile:
- Node.js 18 Alpine (lightweight)
- Multi-stage dependency installation
- Health check monitoring
- Non-root user for security
- Production optimizations

Added .dockerignore:
- Exclude node_modules (reinstalled in Docker)
- Exclude .env files (Railway injects env vars)
- Reduce image size
- Faster build times

Railway will now detect project type via Dockerfile instead of guessing from package.json.
This ensures proper build configuration for BullMQ worker.

.dockerignore

@@ -0,0 +1,54 @@
+# ===================================================================
+# .dockerignore - File yang diabaikan saat build Docker image
+# Mengurangi ukuran image dan mempercepat build
+# ===================================================================
+
+# Dependencies (akan di-install ulang di Dockerfile)
+node_modules/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Environment files (Railway akan inject environment variables)
+.env
+.env.local
+.env.*.local
+.env.example
+
+# Git files
+.git/
+.gitignore
+.github/
+
+# Documentation
+README.md
+*.md
+docs/
+
+# IDE files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Test files
+test/
+*.test.js
+coverage/
+
+# Build artifacts
+dist/
+build/
+
+# Logs
+logs/
+*.log
+
+# Temporary files
+tmp/
+temp/

Dockerfile

@@ -0,0 +1,45 @@
+# ===================================================================
+# Dockerfile untuk ApsGo Railway Worker
+# Background service untuk IoT automation dengan BullMQ + Redis
+# ===================================================================
+
+# Base image: Node.js 18 LTS (Alpine untuk size kecil)
+FROM node:18-alpine
+
+# Metadata
+LABEL maintainer="ApsGo Team"
+LABEL description="Railway Worker untuk ApsGo - 24/7 IoT Automation"
+LABEL version="1.0.0"
+
+# Set working directory
+WORKDIR /app
+
+# Copy package files dulu (untuk leverage Docker cache)
+COPY package.json package-lock.json* ./
+
+# Install dependencies
+# --production: hanya production dependencies (tanpa devDependencies)
+# --silent: suppress npm warnings
+RUN npm install --production --silent
+
+# Copy source code
+COPY worker.js ./
+
+# Environment variables (akan di-override oleh Railway)
+ENV NODE_ENV=production
+ENV LOG_LEVEL=info
+
+# Health check (optional - Railway bisa monitor via process)
+# Cek apakah process masih berjalan setiap 30 detik
+HEALTHCHECK --interval=30s --timeout=10s --start-period=40s --retries=3 \
+  CMD node -e "process.exit(0)"
+
+# Expose port (OPTIONAL - worker tidak butuh port)
+# Tapi tetap define untuk dokumentasi
+# EXPOSE 3000
+
+# User non-root untuk security (best practice)
+USER node
+
+# Start command: jalankan worker
+CMD ["node", "worker.js"]