feat: Add requirements.txt for core dependencies

[johnnyHags]

Overview: This PR introduces a requirements.txt file to manage the project's core Python dependencies.

Changes

• Created requirements.txt at the project root.
• Added fastapi, uvicorn, pydantic, and aiofiles as essential dependencies.
• Ensures a consistent and easily reproducible development environment.
• Establishes the base for future module additions and simplifies dependency management.