fix: downgrade successful log ingestion message to DEBUG

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/LogIngestionController.java

@@ -88,7 +88,7 @@ public class LogIngestionController {
             log.warn("Log buffer full: accepted={}, dropped={} from instance={}, app={}",
                     accepted, dropped, instanceId, applicationId);
         } else {
-            log.info("Accepted {} log entries from instance={}, app={}", accepted, instanceId, applicationId);
+            log.debug("Accepted {} log entries from instance={}, app={}", accepted, instanceId, applicationId);
         }
 
         return ResponseEntity.accepted().build();