feat: add admin billing system, SMTP email, rename to CloudLense

- Add payments, coupons, credits, invoices management to admin dashboard
- Add 7 new admin tabs: Overview, Users, Orgs, Payments, Coupons, Credits, Invoices
- Replace Resend with SMTP email via nodemailer (info@dk0.dev / mail.dk0.dev)
- Add professional branded email templates (alerts, welcome, invoice, credit, password reset)
- Add database migration for payments, coupons, coupon_redemptions, credit_transactions, invoices tables
- Add credit_balance column to organizations
- Add RLS policies for all new tables
- Add 4 new API routes: /api/admin/{payments,coupons,credits,invoices}
- Rename project from website-monitoring to CloudLense
- Update all package.json names and README

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "website-monitoring",
+  "name": "cloudlense-frontend",
   "version": "0.1.0",
   "private": true,
   "scripts": {
@@ -31,6 +31,7 @@
     "lighthouse": "^12.6.1",
     "lucide-react": "^0.477.0",
     "next": "^15.2.4",
+    "nodemailer": "^8.0.1",
     "postcss": "^8.5.3",
     "puppeteer": "^24.7.0",
     "react": "^19.0.0",
@@ -51,6 +52,7 @@
     "@testing-library/jest-dom": "^6.6.3",
     "@testing-library/react": "^16.0.1",
     "@types/node": "^20",
+    "@types/nodemailer": "^7.0.11",
     "@types/react": "^19",
     "@types/react-dom": "^19",
     "concurrently": "^9.1.2",