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/vite.config.ts

@@ -2,11 +2,34 @@ import { defineConfig } from 'vite';
 import react from '@vitejs/plugin-react-swc';
 import tailwindcss from '@tailwindcss/vite';
 import path from 'path';
+import { VitePWA } from 'vite-plugin-pwa';
 
 export default defineConfig({
   plugins: [
     react(),
     tailwindcss(),
+    VitePWA({
+      registerType: 'autoUpdate',
+      strategies: 'injectManifest',
+      srcDir: 'src',
+      filename: 'sw.ts',
+      manifest: {
+        name: 'HealthyFit',
+        short_name: 'HealthyFit',
+        description: 'AI-powered health & fitness tracker',
+        theme_color: '#556B2F',
+        background_color: '#FDFBF7',
+        display: 'standalone',
+        start_url: '/',
+        icons: [
+          { src: '/icons/icon-192.png', sizes: '192x192', type: 'image/png' },
+          { src: '/icons/icon-512.png', sizes: '512x512', type: 'image/png', purpose: 'any maskable' },
+        ],
+      },
+      injectManifest: {
+        globPatterns: [], // no precaching — push handling only
+      },
+    }),
   ],
   resolve: {
     alias: {