feat(clickhouse): add ClickHouseExecutionStore with batch insert for chunked format

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

cameleer3-server-core/src/main/java/com/cameleer3/server/core/ingestion/MergedExecution.java

@@ -0,0 +1,39 @@
+package com.cameleer3.server.core.ingestion;
+
+import java.time.Instant;
+
+/**
+ * A merged execution envelope ready for ClickHouse insertion.
+ * Produced by ChunkAccumulator after receiving the final chunk.
+ */
+public record MergedExecution(
+        String tenantId,
+        long version,
+        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 errorType,
+        String errorCategory,
+        String rootCauseType,
+        String rootCauseMessage,
+        String diagramContentHash,
+        String engineLevel,
+        String inputBody,
+        String outputBody,
+        String inputHeaders,
+        String outputHeaders,
+        String attributes,
+        String traceId,
+        String spanId,
+        boolean hasTraceData,
+        boolean isReplay
+) {}