Complete setup for docker. Add readme, and fix some bugs

backend/Dockerfile

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+# Use the official Node.js image as the base image
+FROM node:20
+
+# Set the working directory inside the container
+WORKDIR /usr/src/app
+
+# Copy package.json and package-lock.json to the working directory
+COPY package*.json ./
+
+# Install the application dependencies
+RUN npm install
+
+# Copy the rest of the application files
+COPY . .
+
+# Build the NestJS application
+RUN npm run build
+
+# Expose the application port
+# EXPOSE 3000
+
+# Command to run the application
+CMD ["node", "dist/main"]