fix: add dashboard to CLI help epilogue and Docker CI smoke test

- Add hermes dashboard examples to the CLI help epilogue so users can
  discover the web UI command from 'hermes --help' output
- Add an independent 'Test dashboard subcommand' CI step that verifies
  'hermes dashboard --help' works in the Docker image, with its own
  mkdir/chown setup to remain independent of the prior smoke test step
- Prevents regressions like #9153 where the dashboard subcommand was
  present in source but missing from the published Docker image

Closes #9153

hermes_cli/_parser.py

@@ -70,6 +70,9 @@ Examples:
     hermes logs --since 1h        Lines from the last hour
     hermes debug share             Upload debug report for support
     hermes update                 Update to latest version
+    hermes dashboard              Start web UI dashboard (port 9119)
+    hermes dashboard --stop       Stop running dashboard processes
+    hermes dashboard --status     List running dashboard processes
 
 For more help on a command:
     hermes <command> --help