Create contributor scoring REST endpoint

[AbdulSnk]

Overview

The StreamForge API needs an endpoint that exposes contributor scoring data to downstream services and the frontend dashboard.

What needs to be done

• Create a scoring module inside src/
• Implement a GET /scoring/:contributor endpoint that returns:
  • contributor (string)
  • total_score (number)
  • breakdown (array of events and their individual scores)
• Connect the endpoint to the scoring logic from StreamForge Core
• Return proper HTTP status codes:
  • 200 on success
  • 404 if contributor not found
  • 400 for malformed requests

Acceptance Criteria

• GET /scoring/:contributor endpoint exists and responds correctly
• Returns correct JSON structure
• Handles contributor not found with 404
• Input validation is in place
• At least one integration test covers the happy path

Notes

Use NestJS conventions — controller, service, and module pattern. Keep the service layer separate from the controller.