fix(billing): surface quota saturation events for admin auditing

Thread int32 saturation clamps from tiered settlement and video task
recompute into the consume/task logs under admin_info, so oversized or
malformed billing inputs stay auditable. Clamp negative audio duration
before token conversion and gate the saturation UI markers on admin.

web/default/src/features/usage-logs/components/dialogs/details-dialog.tsx

@@ -143,6 +143,15 @@ function formatRatio(ratio: number | undefined): string {
   return ratio.toFixed(4)
 }
 
+function quotaSaturationKindLabel(
+  kind: 'overflow' | 'underflow' | 'nan',
+  t: (key: string) => string
+): string {
+  if (kind === 'overflow') return t('Overflow')
+  if (kind === 'underflow') return t('Underflow')
+  return t('Invalid (NaN)')
+}
+
 function BillingBreakdown(props: {
   log: UsageLog
   other: LogOtherData
@@ -704,6 +713,41 @@ export function DetailsDialog(props: DetailsDialogProps) {
           </DetailSection>
         )}
 
+        {/* Quota saturation marker (admin only) */}
+        {props.isAdmin && other?.admin_info?.quota_saturation && (
+          <DetailSection
+            icon={<AlertTriangle className='size-3.5' aria-hidden='true' />}
+            label={t('Quota clamped')}
+            variant='danger'
+          >
+            <p className='mb-1 text-xs wrap-break-word'>
+              {t('Quota saturation protection triggered')}
+            </p>
+            <DetailRow
+              label={t('Kind')}
+              value={quotaSaturationKindLabel(
+                other.admin_info.quota_saturation.kind,
+                t
+              )}
+            />
+            <DetailRow
+              label={t('Original value')}
+              value={String(other.admin_info.quota_saturation.original)}
+              mono
+            />
+            <DetailRow
+              label={t('Clamped to')}
+              value={String(other.admin_info.quota_saturation.clamped)}
+              mono
+            />
+            <DetailRow
+              label={t('Operation')}
+              value={other.admin_info.quota_saturation.op}
+              mono
+            />
+          </DetailSection>
+        )}
+
         {/* Reject reason (admin only) */}
         {props.isAdmin && other?.reject_reason && (
           <DetailSection