A sample Slack app standing in for the user's own app in the demo. It plays the role of the app that receives interactions and events:

• block_actions — either opens a modal (open_config) or acknowledges the click by replying to the response_url.
• view_submission — reads the submitted value and posts a confirmation message into the store.
• view_closed — acknowledged.
• Events API (/events) — handles url_verification challenges and app_mention events by posting a reply into the store.

Mounted at /demo in Slackbox.Demo.Router; the simulator posts here.