Get Grouped Freshness

Tenant's datasets bucketed into UI display groups.

Every timestamp is unix epoch seconds; generated_at carries the server clock so the client can render relative times against it. Internal pipeline dataset_types (dbt transform runs, backfills) are excluded from the response entirely. A databricks tenant always gets groups: [] — the databricks taxonomy classifies every dataset_type to None until it is authored.

Gated by the enableSystemStatus tenant_info flag: a tenant without it gets 404, not an empty payload, so a disabled feature is indistinguishable from one that was never built.