Implement tasks 40, 41, 42: web push, notification bus, reminders engine

Task 40 — Web Push (VAPID):
- Add web-push package + @types/web-push
- pnpm vapid:generate script prints VAPID_PUBLIC_KEY, VAPID_PRIVATE_KEY, NEXT_PUBLIC_VAPID_PUBLIC_KEY
- push_subscriptions schema + migration 0013
- _core/push.ts: sendPush() iterates subscriptions, prunes 404/410 stale entries
- SW push/notificationclick event handlers added to generated sw.js template
- PushOptIn client component on /settings (opt-in, disable, send test)

Task 42 — Notification bus + ntfy adapter:
- notifications table + notif_push/notif_inapp/notif_ntfy user columns (migration 0013)
- _core/notify.ts: notify() fans out to push, in-app DB, and optional ntfy POST
- NotificationBell server component in AppNav: unread badge, dropdown inbox, mark-read
- NotifyChannelToggles client component in /settings

Task 41 — Reminders engine:
- fired_at + created_by added to reminders; default channel changed to 'auto'
- _core/reminders.ts: scheduleReminder (upsert), cancelReminder, listReminders, tickReminders
- tickReminders uses pg_try_advisory_xact_lock for horizontal-scale safety
- src/instrumentation.ts starts reminder worker (30s tick) on Node.js boot
- Notes actions use scheduleReminder/cancelReminder instead of raw SQL
- Calendar createEvent: optional remindMinutesBefore, deleteEvent: cancelReminder
- Calendar-shell: "Remind me 30 min before" checkbox on new event form

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

next.config.ts

@@ -89,6 +89,38 @@ self.addEventListener("fetch", (e) => {
   }
 });
 
+// --- push notifications ---
+
+self.addEventListener("push", (e) => {
+  if (!e.data) return;
+  const data = e.data.json();
+  e.waitUntil(
+    self.registration.showNotification(data.title || "famapp", {
+      body: data.body || "",
+      data: { url: data.url || "/" },
+      icon: "/icon-192.png",
+      badge: "/icon-192.png",
+    })
+  );
+});
+
+self.addEventListener("notificationclick", (e) => {
+  e.notification.close();
+  const url = e.notification.data?.url || "/";
+  e.waitUntil(
+    self.clients
+      .matchAll({ type: "window", includeUncontrolled: true })
+      .then((cs) => {
+        const match = cs.find((c) => c.url.includes(self.location.origin));
+        if (match) {
+          match.focus();
+          return match.navigate(url);
+        }
+        return self.clients.openWindow(url);
+      })
+  );
+});
+
 // --- strategy helpers ---
 
 async function staleWhileRevalidate(request, cacheName) {