Function lifecycle_segment 

pub fn lifecycle_segment(
    rotation_interval_days: Option<u32>,
    expires_at: Option<&str>,
) -> String

Build the at-a-glance lifecycle segment shown after each info row, e.g. rotate 90d expires 2026-09-01. Returns an empty string when neither is set. The expiry is shown as a bare date (the stored time is end-of-day). Public schema, so this renders without a key — same as tags.