[NOTIF-02] Implement Email Notifications

[kilip]

Description

Implement email notifications for enrollment approval and rejection events.

Subtasks

• NOTIF-02-ST-01 Implement NotificationService.send() for email channel
• NOTIF-02-ST-02 Send approval email: congratulations + next steps
• NOTIF-02-ST-03 Send rejection email: notification of rejection
• NOTIF-02-ST-04 Create notifications record with channel: email and update status

Acceptance Criteria

• NOTIF-02-AC-01 Approved member receives email notification
• NOTIF-02-AC-02 Rejected user receives email notification
• NOTIF-02-AC-03 status updated to sent on success, failed on error
• NOTIF-02-AC-04 Email sent even if in-app notification fails (independent channels)

Technical Notes

• Docs: ERD#25-notifications · PRD#61-registration--enrollment-management

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🚀 Phase 5 — Production

Milestone: Phase 5 — Production
Gate: Application live at dash.pkrbt.id, all infra configured, KPI tracking active.