Add supplements, kettlebell, calendar, push notifications, and PWA support

- Supplement tracking: CRUD endpoints, /today, /logs, Supplements page
- Kettlebell workouts: session tracking, analytics endpoint, ActiveSession page
- Calendar module: events CRUD, calendar components
- Push notifications: VAPID keys, PushSubscription model, APScheduler reminders,
  service worker with push/notificationclick handlers, Profile notifications UI
- PWA: vite-plugin-pwa, manifest, icons, service worker generation
- Frontend: TypeScript types, API modules, ConfirmModal, toast notifications
- Auth fixes: password hashing, nutrition endpoint auth
- CLAUDE.md: project documentation and development guide

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/public/push-sw.js

@@ -0,0 +1,39 @@
+self.addEventListener('push', (event) => {
+  console.log('[SW] push received', event.data?.text());
+  if (!event.data) return;
+
+  let title = 'HealthyFit';
+  let body = 'You have a new notification';
+  let url = '/';
+  try {
+    const data = event.data.json();
+    title = data.title;
+    body = data.body;
+    url = data.url ?? '/';
+  } catch {
+    body = event.data.text();
+  }
+
+  event.waitUntil(
+    self.registration.showNotification(title, {
+      body,
+      icon: '/icons/icon-192.png',
+      badge: '/icons/icon-192.png',
+      data: { url },
+    })
+  );
+});
+
+self.addEventListener('notificationclick', (event) => {
+  event.notification.close();
+  const url = event.notification.data?.url ?? '/';
+  event.waitUntil(
+    self.clients
+      .matchAll({ type: 'window', includeUncontrolled: true })
+      .then((clients) => {
+        const existing = clients.find((c) => c.url.includes(url));
+        if (existing) return existing.focus();
+        return self.clients.openWindow(url);
+      })
+  );
+});