Slack: add some fixes and connect it all up

src/slack/index.ts

@@ -12,4 +12,6 @@ export {
   unpinSlackMessage,
 } from "./actions.js";
 export { monitorSlackProvider } from "./monitor.js";
+export { probeSlack } from "./probe.js";
 export { sendMessageSlack } from "./send.js";
+export { resolveSlackAppToken, resolveSlackBotToken } from "./token.js";