9.4.0

### Added

- Extracted `load_reverse_dns_map()` utility function in `utils.py` for loading the reverse DNS map independently of individual IP lookups.
- SIGHUP reload now re-downloads/reloads the reverse DNS map, so changes take effect without restarting.
- Add premade OpenSearch index patterns, visualizations, and dashboards

### Changed

- When `index_prefix_domain_map` is configured, SMTP TLS reports for domains not in the map are now silently dropped instead of being output. Unlike DMARC, TLS-RPT has no DNS authorization records, so this filtering prevents processing reports for unrelated domains.
- Bump OpenSearch support to `< 4`

### Fixed

- Fixed `get_index_prefix` using wrong key (`domain` instead of `policy_domain`) for SMTP TLS reports, which prevented domain map matching from working for TLS reports.
- Domain matching in `get_index_prefix` now lowercases the domain for case-insensitive comparison.

docker-compose.dashboard-dev.yml

@@ -15,7 +15,7 @@ services:
         condition: service_healthy
 
   opensearch-dashboards:
-    image: opensearchproject/opensearch-dashboards:2
+    image: opensearchproject/opensearch-dashboards:3
     environment:
       - OPENSEARCH_HOSTS=["https://opensearch:9200"]
     ports: