Add Stormshield ingest verifier

End-to-end regression test for the SDL Stormshield parser:
- test.py        single upload + 150s polling verifier
- send_burst.py  4 varied events (different users, IPs, actions) with current timestamps
- verify_query.py  query last 15 min of stormshield events
- run_and_verify.sh  burst + 40s wait + verify
- config.example.json  template (config.json is gitignored)
- README.md     setup, run, behaviour-quirks docs

Use against a real SDL tenant after deploying parsers/stormshield. Confirms
parser='stormshield', dataSource.name='Stormshield', and the 5 OCSF rewrites
(src_endpoint.ip/port, dst_endpoint.ip/port, actor.user.name).

.gitignore

@@ -10,3 +10,4 @@ data/
 
 # Parsers ARE committed in this fork (snapshot of the demo tenant).
 # .env still excluded for safety.
+tools/stormshield-verify/config.json