Returns one bucket per granularity unit over the date range, with a count of apps in each of five mutually-exclusive, priority-ordered lifecycle segments for that bucket:

1. risky_apps — scanned with a compliance gap (missing a required framework). Top priority: a risky app is never also counted in another segment.
2. unapproved_apps — not risky, and explicitly marked not approved.
3. ai_apps — not risky, and categorized as an AI app.
4. other_apps — not risky, approved, not AI, and had activity in the bucket.
5. unused_apps — not risky, approved, not AI, with prior usage but no activity in the bucket.

Apps with an unreviewed approval status are excluded from every segment. filter[department_id] and filter[approval_status] (both list, in operator) scope which apps are counted.

This endpoint has no comparison period (period.compare_start_date / compare_end_date are always null) and no pagination — all buckets in the range are returned in a single response.