Provision courses via the Canvas REST API

Verified steps

1. Authenticate with a Canvas API token by passing it as the Authorization header value in the format 'Bearer your_api_token'; for automated provisioning, create a token scoped to the appropriate account via the Canvas admin UI or the API tokens endpoint.
2. POST to /api/v1/accounts/:account_id/courses with a JSON body containing course[name], course[course_code], course[start_at], course[end_at], course[term_id], and course[workflow_state]=available to create a published course.
3. Create sections within the course if needed by POSTing to /api/v1/courses/:course_id/sections with course_section[name] and optional course_section[sis_section_id].
4. Enroll users by POSTing to /api/v1/courses/:course_id/enrollments with enrollment[user_id], enrollment[type] (StudentEnrollment, TeacherEnrollment, etc.), enrollment[enrollment_state]=active, and optionally enrollment[course_section_id].
5. For bulk enrollment of multiple users, POST to /api/v1/accounts/:account_id/bulk_enrollment with user_ids[] and course_ids[] arrays and enrollment_type.
6. Respect Canvas API rate limiting: the API enforces per-token request rate limits and returns a Retry-After header on 403 rate-limit responses; implement exponential backoff and check the X-Rate-Limit-Remaining header to throttle proactively.