feat(clickhouse): wire ChunkAccumulator, flush scheduler, and search feature flag

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

deploy/base/server.yaml

@@ -91,6 +91,8 @@ spec:
                   key: CLICKHOUSE_PASSWORD
             - name: CAMELEER_STORAGE_METRICS
               value: "postgres"
+            - name: CAMELEER_STORAGE_SEARCH
+              value: "opensearch"
 
           resources:
             requests: