feat: email integration (nodemailer) + wire into agency/license flows

- src/lib/email.ts: SMTP client with pre-built templates:
  - sendAgencyApprovedEmail (reseller approval + discount)
  - sendAgencyRejectedEmail (reseller rejection + reason)
  - sendLicenseKeyEmail (license key delivery)
  - sendTicketCreatedEmail (ticket confirmation)
- Agency approve route: sends approval email after DB update
- Agency reject route: sends rejection email with reason
- License creation route: sends license key email (fire-and-forget)
- Graceful degradation: if SMTP not configured, logs warning + continues
- nodemailer + @types/nodemailer installed

package.json

@@ -57,6 +57,7 @@
     "@reactuses/core": "^6.0.5",
     "@tanstack/react-query": "^5.82.0",
     "@tanstack/react-table": "^8.21.3",
+    "@types/nodemailer": "^8.0.2",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",
@@ -71,6 +72,7 @@
     "next-auth": "^4.24.11",
     "next-intl": "^4.3.4",
     "next-themes": "^0.4.6",
+    "nodemailer": "^10.2.1",
     "prisma": "^6.11.1",
     "react": "^19.0.0",
     "react-day-picker": "^9.8.0",