2b226be8e3
Salvaged from #45765 by @navahc09 — kept the PR's callout structure and placement, rewrote the content to match current behavior: Slack blocks native slash commands in threads and never delivers them, so Hermes recognises a leading '!' as an alternate command prefix. Post-C3 command fixes the bang form also works behind a mention (@Hermes !cmd) and with leading whitespace; unknown '!' tokens pass through to the agent unchanged. Cross-linked the detailed slack.md section.