The request.ip property no longer exists on NextRequest in Next.js 15+.
Fall back to x-real-ip (set by trusted reverse proxies) then x-forwarded-for.
The security intent from PR #4 is preserved — x-real-ip is preferred over
the more easily spoofed x-forwarded-for header.
Fixes build error: Property 'ip' does not exist on type 'NextRequest'
a0364ac9f0