Returns the company's active balance groups ("grupos de saldo" / budgets), each with
its computed totals (committable_cents, available_cents, consumed_balance_cents),
its embedded manager, and its bound vendor_cards.

Access

• Admin / finance users (permission budgets_manage) see every group in the company.
• Other users only see the groups they manage (manager_id == their user id).

The company is taken from the company-id header. This endpoint is not paginated —
it returns all active groups in scope.