fix: improve docker security, reliability and default performance

[MathisVerstrepen]

This pull request updates the Docker configuration for the API service to improve security and reliability. The main changes include installing additional dependencies, creating necessary data directories, and ensuring the application runs under a non-root user. The startup command is also updated to use gunicorn instead of uvicorn directly, and ownership of data directories is enforced at container startup.

Security and User Management:

• Installed git and openssh-client in the API Docker image to support repository cloning and SSH operations.
• Ensured the application runs as a non-root user by switching to appuser at container startup in both production and development compose files, using su appuser. [1] [2]

Data Directory Setup:

• Created /app/data/user_files and /app/data/cloned_repos directories in the Docker image to ensure required paths exist for user files and cloned repositories.
• Enforced ownership of /app/data by appuser at container startup to avoid permission issues. [1] [2]

Application Startup Improvements:

• Updated the startup command to use gunicorn with the Uvicorn worker for improved production reliability, replacing the previous direct uvicorn invocation. [1] [2]
• Removed the USER appuser directive from the Dockerfile to allow dynamic user switching at runtime via the compose command.