fix(api): return original email without OAuth suffix in bookings

[pedroccastro]

What does this PR do?

This PR fixes a bug in API v2 (2024-08-13) where emails in booking API responses contained the OAuth client ID as a suffix (+{cuid}). This suffix exists to prevent email collisions between managed users of different OAuth clients.

Fixes #25494 | Linear: CAL-6843

Problem:

• Managed user emails were returned as: [email protected]
• Expected display: [email protected]

Solution: To avoid breaking changes for platform customers who may rely on the original email format, we preserve the original email field and add a new displayEmail field with the CUID suffix removed.

Key Changes:

• Add getDisplayEmail() helper to strip CUID suffix from emails
• Add displayEmail field to all relevant response objects
• Keep original email field unchanged for backwards compatibility

Regex pattern used: /\+[a-zA-Z0-9]{25}/ (CUID format, consistent with google-calendar.service.ts)

Affected Fields

Field	Value
hosts[].email	bob+{cuid}@example.com (unchanged)
hosts[].displayEmail	[email protected] (new)
attendees[].email	bob+{cuid}@example.com (unchanged)
attendees[].displayEmail	[email protected] (new)
bookingFieldsResponses.email	bob+{cuid}@example.com (unchanged)
bookingFieldsResponses.displayEmail	[email protected] (new)
bookingFieldsResponses.guests[]	guest+{cuid}@example.com (unchanged)
bookingFieldsResponses.displayGuests[]	[email protected] (new)
reassignedTo.email	bob+{cuid}@example.com (unchanged)
reassignedTo.displayEmail	[email protected] (new)

How should this be tested?

Test Scenario 1 - Managed user as HOST:

1. Create an event type using managed user's access token
2. Create booking on that event type (external user booking managed user)
3. GET /v2/bookings/{uid} with header Cal-Api-Version: 2024-08-13
4. Verify hosts[].email returns original email with suffix
5. Verify hosts[].displayEmail returns email without suffix

Test Scenario 2 - Managed user as ATTENDEE:

1. Create booking where attendee is a managed user
2. GET /v2/bookings/{uid} with header Cal-Api-Version: 2024-08-13
3. Verify attendees[].email returns original email with suffix
4. Verify attendees[].displayEmail returns email without suffix

Test Scenario 3 - Self-booking:

1. Managed user books their own event type
2. Verify both email and displayEmail fields are present and correct

Expected result: email fields preserve original value, displayEmail fields return clean email without +{cuid} suffix

Mandatory Tasks

• [x] I have self-reviewed the code
• [ ] I have updated the developer docs in /docs if this PR makes changes that would require a documentation change.
• [ ] I confirm automated tests are in place that prove my fix is effective or that my feature works.

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3 Skipped Deployments

Project	Deployment	Review	Updated (UTC)
cal	Ignored		Dec 19, 2025 9:09pm
cal-companion	Ignored	Preview	Dec 19, 2025 9:09pm
cal-eu	Ignored		Dec 19, 2025 9:09pm

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