Retrieves the current account's available credit balance and expected next recurring credit grant time.

The balance is a near-real-time hint and can lag one in-flight metered operation. A 402
response from an operation is authoritative when deciding whether more credits are required.
Negative ledger balances are returned as 0 available credits.

next_grant_at comes from the account's billing schedule, not an existing grant's expiration.
It is null when no scheduled grant can be determined. Processing may occur later, and other
grants may arrive sooner.

Requires api token with one of the following permissions

(any scope allowed)

Tokens with the "Act with a team member's permissions" permission
(all:delegate_to_contact_permissions scope) can also be used. The account is always derived
from the authenticated token; this endpoint does not accept an account identifier.