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>

src/app/settings/page.tsx

@@ -5,12 +5,15 @@ import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { Button } from "@/components/ui/button";
 import { ThemePicker } from "@/components/theme-picker";
 import { CompletionDelaySetting } from "@/components/completion-delay-setting";
+import { PushOptIn } from "@/components/push-opt-in";
+import { NotifyChannelToggles } from "@/components/notify-channel-toggles";
 import { revokeShareLinkAction } from "./actions";
 import Link from "next/link";
 
 export default async function SettingsPage() {
   const { user } = await getCurrentSession();
   const shareLinks = await getActiveShareLinks();
+  const ntfyConfigured = !!(process.env["NTFY_URL"] && process.env["NTFY_TOPIC"]);
 
   return (
     <div className="container max-w-2xl py-8 space-y-6">
@@ -38,6 +41,29 @@ export default async function SettingsPage() {
         </CardContent>
       </Card>
 
+      <Card>
+        <CardHeader>
+          <CardTitle>Push Notifications</CardTitle>
+        </CardHeader>
+        <CardContent>
+          <PushOptIn />
+        </CardContent>
+      </Card>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Notification Channels</CardTitle>
+        </CardHeader>
+        <CardContent>
+          <NotifyChannelToggles
+            push={user.notifPush}
+            inapp={user.notifInApp}
+            ntfy={user.notifNtfy}
+            ntfyConfigured={ntfyConfigured}
+          />
+        </CardContent>
+      </Card>
+
       <Card>
         <CardHeader>
           <CardTitle>Active Share Links</CardTitle>