fix(outbound): null-guard TRUST_PATHS check; add RBAC test for probe endpoint

- OutboundConnectionRequest compact ctor: avoid NPE if tlsTrustMode is null
  (defense-in-depth alongside @NotNull Bean Validation).
- Add operatorCannotTest IT case to lock the ADMIN-only contract on
  POST /{id}/test — was previously untested.

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

cameleer-server-app/src/main/java/com/cameleer/server/app/outbound/dto/OutboundConnectionRequest.java

@@ -30,7 +30,7 @@ public record OutboundConnectionRequest(
         defaultHeaders = defaultHeaders == null ? Map.of() : defaultHeaders;
         tlsCaPemPaths = tlsCaPemPaths == null ? List.of() : tlsCaPemPaths;
         allowedEnvironmentIds = allowedEnvironmentIds == null ? List.of() : allowedEnvironmentIds;
-        if (tlsTrustMode == TrustMode.TRUST_PATHS && tlsCaPemPaths.isEmpty()) {
+        if (tlsTrustMode != null && tlsTrustMode == TrustMode.TRUST_PATHS && tlsCaPemPaths.isEmpty()) {
             throw new IllegalArgumentException("tlsCaPemPaths must not be empty when tlsTrustMode = TRUST_PATHS");
         }
     }