feat: add engineLevel and route-level snapshot fields to ExecutionRecord

Adds engineLevel (NONE/MINIMAL/REGULAR/COMPLETE) and inputBody/outputBody/
inputHeaders/outputHeaders to ExecutionRecord so REGULAR mode route-level
payloads are persisted (previously only processor-level records had payloads).

cameleer3-server-core/src/main/java/com/cameleer3/server/core/storage/ExecutionStore.java

@@ -20,7 +20,9 @@ public interface ExecutionStore {
             String executionId, String routeId, String agentId, String applicationName,
             String status, String correlationId, String exchangeId,
             Instant startTime, Instant endTime, Long durationMs,
-            String errorMessage, String errorStacktrace, String diagramContentHash
+            String errorMessage, String errorStacktrace, String diagramContentHash,
+            String engineLevel,
+            String inputBody, String outputBody, String inputHeaders, String outputHeaders
     ) {}
 
     record ProcessorRecord(