Modernize: express-slack/request -> Bolt, Block Kit buttons, add Docker + deploy

[ddbruce]

Summary

Modernizes air off its abandoned express-slack wrapper and the deprecated request library onto @slack/bolt, converts the Yes/No response buttons to Block Kit (your choice), and adds the container + deploy tooling it never had. Same behavior: a dispatch POST posts to the responding + dispatch channels; during the day-crew window (05:55–18:05) the responding message carries Yes/No buttons; clicking within 12 minutes looks up the user and posts "name is RESPONDING / NOT RESPONDING"; late clicks get the same ephemeral notice.

Verified: 9 unit tests pass; boots on Bolt 4 (/health → 200; dispatch webhook rejects bad verification with 401 and echoes dispatch on good; unsigned /slack/events → 401); amd64 image builds with 0 npm vulnerabilities.

⚠️ Like slack-poll, the live Slack button flow can't be exercised here — please smoke-test in staging.

Changes

• SDK: express-slack (abandoned) + request (deprecated) → @slack/bolt 4.x. Bolt's ExpressReceiver verifies button interactions via the signing secret (the old code did not verify them) and also hosts the external dispatch webhooks (/tmd_slack_notification, /tmd_slack_notification_long) as plain Express routes plus /health. Dropped axios (its only use was the dead OOS check); added dotenv.
• Buttons → Block Kit: the interactive message's Yes/No buttons are now Block Kit (action_id responding_yes/responding_no, values yes/no) placed inside a colored attachment so the orange color bar is preserved. The other non-interactive messages keep their colored attachments unchanged.
• Config externalized to env vars (.env + dotenv): SLACK_BOT_TOKEN, SLACK_SIGNING_SECRET (new), AIR_CHANNEL, DISPATCH_CHANNEL, VERIFICATION_TOKEN, PORT (default 5939). Removes the hardcoded channel IDs + port, the var.js/data.json config & OAuth store, and the express-slack OAuth scopes.
• Packaging: added a Dockerfile (there was none) — node:24-alpine, npm ci, non-root, HEALTHCHECK; ESLint 9 flat config; Jest tests; GitHub Actions CI; scripts/deploy.sh + config.example.sh.

⚠️ Required Slack app config changes

1. Interactivity Request URL → https://<host>/slack/events (was /slack_response).
2. Add a Signing Secret (SLACK_SIGNING_SECRET) — from the Slack app's Basic Information. The old code didn't verify button requests at all; Bolt requires it.
3. The external dispatch system keeps POSTing to /tmd_slack_notification / _long with the verification field (now VERIFICATION_TOKEN) — unchanged.

🐞 Pre-existing bug — your call (NOT silently changed)

The original out-of-service override (areOos()) called axios.get(...) without await and compared a Promise to 1, so it always evaluated false and never affected which message was posted. I preserved that behavior (the override stays disabled) rather than change it silently. OOS_URL/OOS_TOKEN remain in config. Want me to actually enable the OOS check (so off-hours OOS calls show the responding message)? Say the word and I'll wire it up with proper await + error handling.

Verify in staging

1. Fire a test dispatch to /tmd_slack_notification during the day → Yes/No buttons appear; click each → status message posts with the right name.
2. Fire one outside 05:55–18:05 → "Night crew call. No response is needed." (no buttons).
3. /tmd_slack_notification_long → longtone notices in both channels.
4. Click a button >12 min after dispatch → the "too long after" ephemeral.

Recommended follow-ups (NOT done)

• Decide on the OOS override (above).
• Reconcile license metadata (LICENSE = MIT vs package.json = ISC).