**Description**
Currently, the `organizer` attendee object in webhook payloads and event API responses does not include a stable user identifier. The only available identifier is `organizer.email`, which is mutable and therefore unreliable for automation use cases.
**Use case**
When building automations on top of SavvyCal webhooks (e.g. via tools like Activepieces, Zapier, Make), a common need is to route or filter flows based on which specific team member hosted a booking — for example:
- Syncing bookings to a CRM and associating them with the right sales rep
- Triggering different actions depending on the assigned host in a round-robin setup
- Reporting per-host booking stats
`user.id` is already stable and unique per SavvyCal account (confirmed by your support team). It just needs to be surfaced on the `organizer` attendee object.
**Proposed change**
Add a `user_id` (or `user.id`) field to the `organizer` attendee object in:
- Webhook payloads (all event types)
- `GET /v1/events` and `GET /v1/events/:id` API responses
This would be a non-breaking additive change and would unlock reliable host identification for any integration built on top of SavvyCal's API.
