[TASK] Application Containerization (Backend & Frontend)

[PEXEL2002]

Task description and detailed requirements:
Prepare Dockerfiles for the application code to ensure environment consistency between Windows 11 and Fedora.

• Create a Dockerfile for the FastAPI backend (using python:3.11-slim).
• Integrate the backend into the existing docker-compose.yml.
• (Optional) Prepare a basic Dockerfile for the React frontend.

Definition of task completion:
The entire stack (DBs + Backend) can be built and started with a single command, and the FastAPI "docs" page is reachable at localhost:8000/docs.