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>

package.json

@@ -1,8 +1,8 @@
 {
-  "name": "website-monitoring",
+  "name": "cloudlense",
   "version": "1.0.0",
   "private": true,
-  "description": "Full-stack website monitoring platform with Lighthouse performance auditing",
+  "description": "CloudLense — Full-stack website monitoring & performance auditing platform",
   "scripts": {
     "setup": "bash dev-setup.sh",
     "start": "cd frontend && supabase start && cd .. && concurrently -n db,backend,frontend -c blue,yellow,green \"echo Supabase ready\" \"npm run dev:backend\" \"npm run dev:frontend\"",