feat: rebrand to Domain Scanner platform

Replace GeoExport static site with Next.js domain intelligence app:
real DNS/WHOIS/SSL/HTTP/geo scans, SSE progress, Docker stack,
updated install/uninstall scripts, and full documentation.

Co-authored-by: Cursor <cursoragent@cursor.com>

.env.example

@@ -0,0 +1,8 @@
+# Domain Scanner
+DATABASE_URL=postgresql://scanner:scanner@localhost:5432/domain_scanner?schema=public
+REDIS_URL=redis://localhost:6379
+NEXTAUTH_URL=http://localhost:3000
+NEXTAUTH_SECRET=change-me-to-a-long-random-string
+NEXT_PUBLIC_APP_URL=http://localhost:3000
+IPINFO_TOKEN=
+SCAN_RATE_LIMIT_PER_HOUR=30