feat: add application log ingestion with OpenSearch storage

Agents can now send application log entries in batches via POST /api/v1/data/logs.
Logs are indexed directly into OpenSearch daily indices (logs-{yyyy-MM-dd}) using
the bulk API. Index template defines explicit mappings for full-text search readiness.

New DTOs (LogEntry, LogBatch) added to cameleer3-common in the agent repo.

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

cameleer3-server-app/src/main/resources/application.yml

@@ -42,6 +42,8 @@ opensearch:
   index-prefix: ${CAMELEER_OPENSEARCH_INDEX_PREFIX:executions-}
   queue-size: ${CAMELEER_OPENSEARCH_QUEUE_SIZE:10000}
   debounce-ms: ${CAMELEER_OPENSEARCH_DEBOUNCE_MS:2000}
+  log-index-prefix: ${CAMELEER_LOG_INDEX_PREFIX:logs-}
+  log-retention-days: ${CAMELEER_LOG_RETENTION_DAYS:7}
 
 cameleer:
   body-size-limit: ${CAMELEER_BODY_SIZE_LIMIT:16384}