# Add GitHub Classroom GetAssignment API endpoint

Implements `GET /assignments/{assignment_id}` endpoint for retrieving GitHub Classroom assignment details.

## Changes

- **New service**: `ClassroomService` with `GetAssignment()` method
- **New structs**: `Assignment` (19 fields) and `Classroom` with organization details

Refactors the Assignment struct and related methods to ClassroomAssignment for improved clarity and consistency. Updates all accessors, service methods, and tests to use the new name.