Retrieve checkout sessions with rich filtering, sorting, and pagination.

Filter by:

• Status: checkout_session_status (open, processing, completed, closed, cancelled), payment_status (not_started, pending, paid, failed, no_payment_required).
• Dates: created_at, confirmed_at, paid_at, last_activity_at (range filters supported).
• Customer: customer_id, guest_checkout, business_entity_id.
• Contract: contract_id, currency.

Pagination & sorting:

• limit: page size (1-100).
• cursor: pass 'next' from previous response to paginate.
• order: field to sort by (e.g., -created_at for desc).