One filtered page of tenants with their licences and seat usage.

The list screen used to read /overview, which returns every tenant with every licence in a single payload and leaves filtering to the browser. That cannot be paged: filtering a page instead of the table drops matches that sit on other pages, so the two have to move together. /overview stays what its docstring says it is — a dashboard aggregate of KPIs and per-app totals.

An envelope here, unlike /users/count, because this route is new and has no callers to break. It also saves a round-trip: a page is meaningless without the total behind it.