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/components/app-nav.tsx

@@ -1,14 +1,36 @@
 import Link from "next/link";
 import { Settings } from "lucide-react";
+import { desc, eq } from "drizzle-orm";
 import { getRegistry } from "@/modules/_core/registry";
 import type { DashboardMeta } from "@/app/d/actions";
+import { notifications } from "@/modules/_core/schema";
+import { db } from "@/lib/db";
+import { auth } from "@/lib/auth";
 import { DashboardSwitcher } from "./dashboard-switcher";
 import { DashboardTab } from "./dashboard-tab";
+import { NotificationBell } from "./notification-bell";
 
-export function AppNav({ dashboards = [] }: { dashboards?: DashboardMeta[] }) {
+async function getNotifications(userId: string) {
+  const rows = await db
+    .select()
+    .from(notifications)
+    .where(eq(notifications.userId, userId))
+    .orderBy(desc(notifications.createdAt))
+    .limit(20);
+  const unread = rows.filter((n) => !n.readAt).length;
+  return { rows, unread };
+}
+
+export async function AppNav({ dashboards = [] }: { dashboards?: DashboardMeta[] }) {
   const { modules } = getRegistry();
   const navItems = modules.flatMap((m) => (m.nav ? [m.nav] : []));
 
+  const session = await auth();
+  const userId = session?.user?.id;
+  const { rows: notifRows, unread } = userId
+    ? await getNotifications(userId)
+    : { rows: [], unread: 0 };
+
   return (
     <header className="border-b">
       <nav className="px-4 py-3 flex items-center gap-6">
@@ -24,13 +46,27 @@ export function AppNav({ dashboards = [] }: { dashboards?: DashboardMeta[] }) {
             {item.label}
           </Link>
         ))}
-        <Link
-          href="/settings"
-          className="ml-auto text-muted-foreground hover:text-foreground transition-colors"
-          aria-label="Settings"
-        >
-          <Settings className="size-4" />
-        </Link>
+        <div className="ml-auto flex items-center gap-3">
+          {userId && (
+            <NotificationBell
+              initialUnread={unread}
+              initialItems={notifRows.map((n) => ({
+                id: n.id,
+                title: n.title,
+                body: n.body,
+                url: n.url ?? null,
+                createdAt: n.createdAt,
+              }))}
+            />
+          )}
+          <Link
+            href="/settings"
+            className="text-muted-foreground hover:text-foreground transition-colors"
+            aria-label="Settings"
+          >
+            <Settings className="size-4" />
+          </Link>
+        </div>
       </nav>
 
       {dashboards.length > 0 && (