feat: add hashedLink to BOOKING_REQUEST/CREATED webhooks payload via RegularBookingService

[ThyMinimalDev]

What does this PR do?

This PR adds the hashedLink field to the BOOKING_ webhooks payload, allowing webhook consumers to identify when a booking was made via a private link and which specific link was used.

Changes:

• Added hashedLink field to the CalendarEvent type definition
• Added withHashedLink() method to CalendarEventBuilder for setting the hashedLink
• Updated RegularBookingService to pass the hashedLink from the booking request to the CalendarEvent

The hashedLink is automatically included in webhook payloads via the existing spread operator in getWebhookPayloadForBooking, which spreads the entire CalendarEvent object into the payload.

Link to Devin run: https://app.devin.ai/sessions/97d690b2c1ae4f5895daa06bd8f5a32e
Requested by: [email protected] (@ThyMinimalDev)

Mandatory Tasks (DO NOT REMOVE)

• I have self-reviewed the code (A decent size PR without self-review might be rejected).
• I have updated the developer docs in /docs if this PR makes changes that would require a documentation change. If N/A, write N/A here and check the checkbox.
• I confirm automated tests are in place that prove my fix is effective or that my feature works.

How should this be tested?

1. Create a private link for an event type that requires confirmation
2. Book via the private link (e.g., /d/{hashedLink}/{eventSlug})
3. Set up a webhook subscriber for BOOKING_REQUESTED events
4. Verify the webhook payload includes the hashedLink field with the correct link token value
5. Verify bookings made without a private link have hashedLink as null or undefined

Expected behavior:

• When booking via private link: hashedLink should contain the link token (e.g., "sgdthj8mu4nsLNTYi3fW2p")
• When booking via regular link: hashedLink should be null or undefined

Important Review Points

⚠️ Critical areas to review:

1. Webhook payload verification: Confirm that hashedLink actually appears in the webhook payload by tracing through getWebhookPayloadForBooking → webhook delivery
2. Other booking paths: Check if there are other booking creation flows (API v2, reschedule, etc.) that also need to include hashedLink
3. Field population logic: Verify the condition hasHashedBookingLink ? reqBody.hashedLink ?? null : null correctly identifies private link bookings
4. No tests added: This PR does not include automated tests for the new field in webhook payloads
5. Backward compatibility: Confirm existing webhook consumers won't break with the new optional field

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR that start with 'DevinAI' or '@devin'.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

2 Skipped Deployments

Project	Deployment	Preview	Comments	Updated (UTC)
cal	Ignored			Nov 20, 2025 7:49am
cal-eu	Ignored			Nov 20, 2025 7:49am

[cubic-dev-ai]

No issues found across 3 files

[github-actions]

E2E results are ready!

• Workflow #89260.1 latest results