checkpoint ISAC registries and system monitoring

docs/DEPLOYMENT.md

@@ -288,6 +288,14 @@ Transparent icon uploads skip remove.bg. Opaque sources use its preview output,
 then pass through local trimming, white normalization, WebP conversion, and
 storage.
 
+The application stores a remove.bg capacity snapshot and refreshes it from the
+internal scheduler. `REMOVE_BG_CREDIT_CHECK_HOURS` controls the account lookup
+interval and defaults to six hours. Low-capacity alerts require both remaining
+pools to cross their thresholds: `REMOVE_BG_LOW_CREDIT_THRESHOLD` defaults to
+five paid credits, and `REMOVE_BG_LOW_FREE_CALL_THRESHOLD` defaults to ten free
+calls. Alerts are mandatory ISAC notifications for active Administrators and
+are deduplicated for each warning or critical episode.
+
 ```sh
 npm run images:export
 ```