CVE-2026-71479: New API: Integer overflow in quota billing yields negative charges (self-crediting)

Multiple billing paths multiplied user-controlled quantity parameters into the quota calculation without an upper bound or overflow-safe integer conversion. A crafted extreme value (e.g. image n = 18446744073686646784, a wrapped-negative accepted by a *uint field) makes conversions like int(float64(quota) * n) wrap past the int64/int32 range into a large negative quota. The negative quota takes effect at settlement (not at pre-consume), where it is equivalent to crediting the user’s balance — turning a small positive balance into an enormous one.