feat(webhook): time-series histogram stats endpoint + frontend chart

ordinis-admin-ui/src/api/client.ts

@@ -330,6 +330,24 @@ export type WebhookDeliveryPage = {
   size: number
 }
 
+/** Один bucket histogram time-series stats. ISO ts + counts по status. */
+export type WebhookStatsBucket = {
+  ts: string
+  pending: number
+  retrying: number
+  delivered: number
+  dlq: number
+  total: number
+}
+
+/** Response от GET /admin/webhooks/subscriptions/{id}/stats. */
+export type WebhookDeliveryStats = {
+  bucketBy: 'hour' | 'day'
+  from: string
+  to: string
+  buckets: WebhookStatsBucket[]
+}
+
 // === Approval Workflow v2 ===
 
 export type DraftStatus = 'PENDING' | 'APPROVED' | 'REJECTED' | 'WITHDRAWN'