feat(lib): notify() stub for pulse-opened events

Today this just logs to console. Wired up in step 10's admin pulse-publish
handler so the integration point exists from day one — only the body
changes when we pick a transactional email or Slack webhook later.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/notify.ts

@@ -0,0 +1,16 @@
+import type { PulseRow } from './db.js';
+
+/**
+ * Fired when an admin promotes a pulse from draft → open. Today this is a
+ * console.log stub; the integration (transactional email or Slack webhook)
+ * lands in a later phase. The call site stays the same once wired up — only
+ * this function body changes.
+ *
+ * TODO: replace with the production notifier when chosen. Likely options:
+ *  - Postmark / Resend transactional email to all CAB members
+ *  - Slack webhook to a council-only channel
+ */
+export function notifyPulseOpened(pulse: PulseRow): void {
+  // eslint-disable-next-line no-console
+  console.log(`[notify] pulse opened: "${pulse.question}" — closes ${pulse.closes_at}`);
+}