[BACKEND] Confirmation email

[aleckshen]

Is your feature request related to a problem? Please describe

When a user successfully registers for an event, they receive no confirmation — there is no email sent to acknowledge their registration.

Describe the solution you'd like

Create a reusable sendRegistrationConfirmation function at src/lib/email/registrationConfirmation.ts. Once both this ticket and #12 are merged, the function will be called at the end of the checkCapacity hook after all checks pass.

Function signature:

sendRegistrationConfirmation({
  to: string,
  eventTitle: string,
  eventDate: string,
  eventTime: string,
  eventLocation: string,
})

Email content:

• Subject: You're registered for {eventTitle}!
• Body: confirmation message including event title, date, time, and location, signed off as the UOAVC Team

Error handling: wrap payload.sendEmail() in a try/catch — email failures should be logged but must not throw, since a failed email should never block a registration from being saved.

Once both this ticket and Ticket 6 are merged, add the email call to the end of checkCapacity.ts, using req.user?.email for logged-in users or data.guestEmail for guests.

Describe alternatives you've considered

No alternatives considered — a standalone utility function keeps email logic decoupled from the hook and makes it easy to reuse elsewhere (e.g. waitlist confirmations in a future sprint).

Additional context

Depends on email being configured (#11). If email is not yet set up, the function will catch the error, log it, and return gracefully — this is acceptable during development.

Ref: https://payloadcms.com/docs/email/overview

BEFORE MERGING

• Code generation run (hint: pnpm typegen)
• PR Reviewed (For non-trivial changes)
• All required PR checks passing