chore(deploy): Dockerize the frontend and backend applications

[Zafar7645]

User Story: As a developer, I want to containerize the application so it can be deployed consistently and reliably.

Acceptance Criteria:

• Create a Dockerfile for the NestJS backend.
• Create a multi-stage Dockerfile for the Angular frontend to build the app and serve it via a lightweight web server like Nginx.
• Create a docker-compose.yml file in the root of the monorepo to orchestrate the backend, frontend, and a PostgreSQL database service.
• Ensure the entire application can be started with a single docker-compose up command.