feat(license): add AuditCategory.LICENSE

Tasks downstream (LicenseService, LicenseEnforcer) audit under
this category for install_license / replace_license / reject_license
/ revalidate_license / cap_exceeded actions.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cameleer-server-core/src/main/java/com/cameleer/server/core/admin/AuditCategory.java

@@ -4,5 +4,6 @@ public enum AuditCategory {
     INFRA, AUTH, USER_MGMT, CONFIG, RBAC, AGENT,
     OUTBOUND_CONNECTION_CHANGE, OUTBOUND_HTTP_TRUST_CHANGE,
     ALERT_RULE_CHANGE, ALERT_SILENCE_CHANGE,
-    DEPLOYMENT
+    DEPLOYMENT,
+    LICENSE
 }