feat(128): erli orders import

Phase 128 complete:
- add Erli /inbox order import with safe mark-read ACK
- add cron/manual import controls and sync state tracking
- map Erli orders into orderPRO aggregates with mapper tests and docs

src/Core/Constants/IntegrationSources.php

@@ -8,6 +8,7 @@ final class IntegrationSources
 {
     public const ALLEGRO = 'allegro';
     public const SHOPPRO = 'shoppro';
+    public const ERLI = 'erli';
     public const APACZKA = 'apaczka';
     public const INPOST  = 'inpost';
 }