Nightscout simulator

This pretends to be a Nightscout instance with a Loop app behind it. It exists so CarbSnap's development environment can exercise the entire command path — headers, one-time password, payload shape, response handling — without anything reaching a real insulin pump.

No pump. No person. Nothing here affects anyone. Production is configured never to send commands here, so a simulated Loop cannot stand in for a real one.

Failure modes can be forced with ?fail=:

• devicetoken — Loop never published a device token
• otp — the one-time password is rejected on the phone
• auth / readonly — API secret refused, or read-only
• dosingoff — automated dosing switched off
• nopresets — no override presets configured
• noglucose / nodevicestatus / staleprofile / apns