Feature: Implement a Reporter Module

[c21051997]

Is your feature request related to a problem? Please describe.
The current library requires the end-user to write their own boilerplate code (using rich or other tools) to display the evaluation results. This is repetitive and adds friction to using the library.

Describe the solution you'd like
Create a new ragscope.reporters module with functions that take a list of EvaluationResult objects and automatically generate beautiful reports.

Initial supported formats should include:

• rich_reporter(): To print the console table we currently have in the example.
• json_reporter(): To export the full results to a JSON file.
• html_reporter(): To generate a shareable, self-contained HTML report.

Describe alternatives you've considered
Leaving it to the user is the current alternative, but a built-in reporter would be a much better user experience.

Additional context
This will make the tool much easier and faster to use.