Returns aggregate counts for the organization, used by the Workbench Dashboard Metrics widget:

• by_time_bucket — scheduled (pending|queued) counts in the
  overdue bucket (execution_datetime already past — exactly what
  the next cron tick will pick up) plus the cumulative forward
  windows next_1h ⊆ next_4h ⊆ next_24h, anchored at query
  time. Buckets are disjoint from overdue, so
  overdue + next_24h reconciles with the total scheduled within
  24 hours.
• by_status_over_time — hourly status-transition counts over the
  trailing 24 hours. Sparse: only (bucket, status) pairs with a
  non-zero count are returned.
• total — grand total honouring the filters.

Hidden instructions are included only when the requester holds instructions:read_hidden.

Permission: instructions:read (plus instructions:read_hidden to include hidden instructions in the counts).