Added dockerfile and dockerignore for backend.

Backend/.dockerignore

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+node_modules/
+package-lock.json
+Dockerfile

Backend/Dockerfile

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+# Base image
+FROM node:22
+
+# Metadata
+LABEL maintainer="kshitijka"
+LABEL version=1.1.0
+LABEL description="Crop Compass is a centralized management dashboard designed for farmers, enabling them to efficiently oversee their farms while leveraging advanced AI technology for disease identification and more."
+
+# Update and upgrade
+RUN apt update && apt upgrade -y && \
+    apt clean all && \
+    rm -rf /var/lib/apt/lists/*
+
+# Create non-root user
+RUN useradd -s /bin/bash nonroot
+
+# Create working directory
+RUN mkdir -p /app
+RUN chown -R nonroot:nonroot /app
+WORKDIR /app
+COPY . .
+
+# Generate a random hex token and write it to .env
+RUN echo "REFRESH_TOKEN_SECRET=$(openssl rand -hex 32)" >> /app/.env
+RUN npm install
+
+# Switch user
+USER nonroot
+
+# Expose backend port
+EXPOSE 8000
+
+# Run backend
+CMD ["node", "index.js"]