Returns the total number of non-deleted human users across all non-deleted tenants,
excluding the platform (root) tenant — its users are administered on the dedicated
platform-users surface. The counted tenant set is therefore identical to the one
GET /api/v3/admin/platform/tenants returns minus the caller's own tenant, so this
count and that tenant list always share the same denominator.

Tenant status is not filtered: a suspended tenant's users are still counted, exactly
as a suspended tenant still appears in the tenant list. Soft-deleted users and
soft-deleted tenants are excluded.

Users pending activation are counted in totalUsers AND reported separately in
pendingUsers, a subset of the total (0 <= pendingUsers <= totalUsers), so the
fully-onboarded population is totalUsers - pendingUsers. The platform has no
PENDING_ACTIVATION status — a pending user is stored ACTIVE with
requirePasswordChange = true — and a suspended or disabled user is never counted as
pending.

Issues exactly two queries: tenant ID resolution and a single aggregate that yields both
counts in one pass (never two COUNTs, which could otherwise report more pending users
than total across concurrent writes).

Authorization: Requires platform.analytics.read scope (platform admins only).