List birthdays (v2)

Return every contact that has a stored birthday, as a light card projection: { data: { birthdays: [{ contact_id, full_name, image_url, job_title, company, birthday_month, birthday_day, birthday_year, ...socials, contact_emails, contact_phone_numbers }] } }. Ordered by month then day. Powers the Birthdays page (today / upcoming / by-month groupings are computed client-side).