patch
https://example.com/api/v1/alerts/subscriptions//
ViewSet for alert rule subscriptions.
Routes:
- GET /api/v1/alerts/subscriptions/ - List user's subscriptions
- POST /api/v1/alerts/subscriptions/ - Subscribe to a rule (with rule_id in body)
- DELETE /api/v1/alerts/subscriptions/{rule_id}/ - Unsubscribe from a rule