`POST /api/v1/notifications/channels`, create a notification channel.
POST/api/v1/notifications/channels
Validates the channel, inserts it into notifications.db, then reloads the
[NotificationEngine] via its handle.
Request
Responses
- 201
- 409
- 422
- 500
- 503
Channel created
Channel id already exists
Validation error
Repository error
Notification repository unavailable