Add bulk course enrollment API endpoint with transaction wrapper

[RUKAYAT-CODER]

Overview

Admins and instructors currently enroll students one at a time via individual API calls. Enrolling a cohort of 500 students requires 500 sequential requests, is slow, and risks partial failure leaving students in inconsistent enrollment states.

Specifications

Features:

• POST /enrollments/bulk accepts an array of { userId, courseId } pairs.
• Entire batch succeeds or fails atomically inside a database transaction.

Tasks:

• Create BulkEnrollmentDto with @ArrayMaxSize(500) validation.
• Implement EnrollmentsService.bulkEnroll() using TypeORM QueryRunner transaction.
• Return a summary: { enrolled: N, skipped: N, failed: N, errors: [] }.
• Add rate limiting on the bulk endpoint (max 1 request/minute per user).
• Add integration tests for partial failure rollback.

Impacted Files:

• src/courses/enrollments/ (service and controller)

Acceptance Criteria

• Partial validation failure rolls back all enrolled records.
• Response includes per-item error details for skipped records.
• Bulk enroll 500 users in under 2 seconds.

[nanaabdul1172]

@nanaabdul1172 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello,

I'd like to work on this issue. I can implement a transactional bulk enrollment endpoint with DTO validation, rate limiting, detailed result reporting, and integration tests to ensure atomic rollback on failure. I'll also verify the implementation is performant and meets the specified acceptance criteria.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @nanaabdul1172 to this issue.

[laxjovial]

@laxjovial has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

please i can work on this, please kindly assign to me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @laxjovial to this issue.

[drips-wave]

Congratulations, @laxjovial! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @laxjovial: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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