Classify each dictionary item into a difficulty level.

[wammar]

Why is this needed? Our UX research concluded that we want to offer users the option to specify the difficulty level of jargon definitions. In order to do that, we need to systematically label each definition.
 
Subtasks:

• Decide on a classification system (e.g., low, medium, high).
• Set thresholds.
• Evaluation.
• Implement the API call for it.

[wammar]

Acceptance criteria:

• Add an endpoint definition to the existing OpenAPI file, which takes as input (a term and a definition), and returns a string.
• Implementation in FastAPI (leveraging the code Jen already wrote).
• OpenAPI documentation.

[jonjiang1]

FastAPI documentation and tutorial for setting up a new path/endpoint https://fastapi.tiangolo.com/tutorial/path-params/

[wammar]

@zepam Are you still planning to implement the API interface for this?

Jonathan suggests that the API interface is not required, and we can integrate this module as a subprocess in the simplification module instead. I'm OK either way based on the revised architecture as of May 24.