Flag idle software seats before they renew

Software subscriptions pile up: seats nobody uses, renewals that fire unnoticed. An agent flags idle seats for each tool's owner, but only when the renewal is close enough to act on.

Write flag_renewal_window_idle_seats(seat_lines, idle_threshold_days, renewal_lead_days): the rule your agent follows for each seat.

• seat_lines (list of str): one seat each, written tool|user|idle_days|kind|days_to_renewal, for example "figma|alice|95|human|40". A kind of service marks a service account. idle_days and days_to_renewal are whole numbers.
• idle_threshold_days (int): how long a seat must be idle to count.
• renewal_lead_days (int): how far ahead of a renewal the agent starts flagging.
• Return "tool:user" for every flagged seat, sorted in ascending order. A row that appears twice is flagged twice.

Rules, for each row:

1. Skip a row that does not split on | into exactly 5 fields.
2. Skip a service account (kind exactly service).
3. Skip a seat idle for fewer than idle_threshold_days.
4. Skip a seat whose days_to_renewal is 0 or less, or above renewal_lead_days.
5. Flag the rest.