Production upgrade: Clerk auth, Stripe billing, analytics, PWA support

Backend & Auth:
- Add @clerk/nextjs for production authentication
- Create src/proxy.ts with clerkMiddleware() for route protection
- Implement multi-tenant auth with role-based access control
- Add Clerk components (Show, UserButton, SignInButton, SignUpButton)

Billing & Payments:
- Full Stripe integration (subscriptions, add-ons, customer portal)
- Plan tiers: Starter 9/mo, Farm 49/mo, Enterprise 99/mo
- Webhook handling for subscription events
- createSubscription(), createAddonSubscription(), createCustomerPortalSession()

API & Security:
- Rate limiting with @upstash/ratelimit (100 req/min API, 20 req/min checkout)
- Zod validation schemas for all endpoints (orders, products, campaigns, etc.)
- Security headers (CSP, HSTS, X-Frame-Options)
- API routes: /api/v1/ with validated, rate-limited endpoints

Monitoring:
- Sentry error tracking with performance monitoring
- PostHog analytics for feature usage, funnels, cohorts
- User activity logging and breadcrumb tracking

Admin Features:
- Analytics dashboard with revenue charts, customer growth, conversion funnel
- Onboarding flow with 6-step interactive tour
- Referral system with share tracking and reward redemption
- Changelog feed with in-app notifications

PWA & SEO:
- Web app manifest with icons and shortcuts
- Service worker for offline support and caching
- Full SEO metadata, OpenGraph, Twitter cards
- Structured data (JSON-LD) for organization and products

Database:
- Add referral_codes, changelogs, onboarding_progress tables
- Add user_activity_logs, api_keys, notification_preferences
- Comprehensive RLS policies for all new tables
- Seed data for demo brands and products

src/lib/pwa.ts

@@ -0,0 +1,141 @@
+// PWA Registration and Service Worker management
+
+export function registerServiceWorker() {
+  if (typeof window === 'undefined' || !('serviceWorker' in navigator)) {
+    return;
+  }
+
+  window.addEventListener('load', async () => {
+    try {
+      const registration = await navigator.serviceWorker.register('/sw.js', {
+        scope: '/',
+      });
+
+      // Handle updates
+      registration.addEventListener('updatefound', () => {
+        const newWorker = registration.installing;
+        if (newWorker) {
+          newWorker.addEventListener('statechange', () => {
+            if (newWorker.state === 'installed' && navigator.serviceWorker.controller) {
+              // New content available, prompt user to refresh
+              showUpdatePrompt();
+            }
+          });
+        }
+      });
+
+      console.log('Service Worker registered:', registration.scope);
+    } catch (error) {
+      console.error('Service Worker registration failed:', error);
+    }
+  });
+}
+
+function showUpdatePrompt() {
+  // Dispatch custom event for UI to handle update prompt
+  const event = new CustomEvent('sw-update-available');
+  window.dispatchEvent(event);
+}
+
+export function requestNotificationPermission() {
+  if (!('Notification' in window) || !('serviceWorker' in navigator)) {
+    return Promise.resolve(false);
+  }
+
+  return Notification.requestPermission();
+}
+
+export async function subscribeToPush(registration: ServiceWorkerRegistration) {
+  if (!('PushManager' in window)) {
+    return null;
+  }
+
+  try {
+    const subscription = await registration.pushManager.subscribe({
+      userVisibleOnly: true,
+      applicationServerKey: urlBase64ToUint8Array(
+        process.env.NEXT_PUBLIC_VAPID_PUBLIC_KEY || ''
+      ),
+    });
+
+    console.log('Push subscription:', subscription);
+    return subscription;
+  } catch (error) {
+    console.error('Push subscription failed:', error);
+    return null;
+  }
+}
+
+function urlBase64ToUint8Array(base64String: string): Uint8Array {
+  const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
+  const base64 = (base64String + padding).replace(/-/g, '+').replace(/_/g, '/');
+  const rawData = window.atob(base64);
+  const outputArray = new Uint8Array(rawData.length);
+
+  for (let i = 0; i < rawData.length; ++i) {
+    outputArray[i] = rawData.charCodeAt(i);
+  }
+
+  return outputArray;
+}
+
+// Check if app is installed (PWA)
+export function isPWAInstalled(): boolean {
+  return (
+    window.matchMedia('(display-mode: standalone)').matches ||
+    (window.navigator as { standalone?: boolean }).standalone === true
+  );
+}
+
+// Get install prompt
+export function getInstallPrompt(): { prompt: () => void; outcome: Promise<'accepted' | 'dismissed' | 'canceled'> } | null {
+  if (!('beforeinstallprompt' in window)) {
+    return null;
+  }
+
+  let deferredPrompt: beforeinstallpromptEvent | null = null;
+
+  window.addEventListener('beforeinstallprompt', (event) => {
+    event.preventDefault();
+    deferredPrompt = event;
+  });
+
+  return {
+    prompt: () => {
+      if (deferredPrompt) {
+        deferredPrompt.prompt();
+      }
+    },
+    outcome: new Promise((resolve) => {
+      if (deferredPrompt) {
+        deferredPrompt.userChoice.then((choiceResult) => {
+          deferredPrompt = null;
+          resolve(choiceResult.outcome as 'accepted' | 'dismissed' | 'canceled');
+        });
+      } else {
+        resolve('dismissed');
+      }
+    }),
+  };
+}
+
+// Share API for native sharing
+export async function shareContent(content: {
+  title: string;
+  text: string;
+  url?: string;
+}): Promise<boolean> {
+  if (!navigator.share) {
+    return false;
+  }
+
+  try {
+    await navigator.share(content);
+    return true;
+  } catch (error) {
+    if ((error as Error).name !== 'AbortError') {
+      console.error('Share failed:', error);
+    }
+    return false;
+  }
+}