request /{station}
      │
      ▼
 ┌─────────────┐   45s hold    ┌──────────────┐
 │  Edge cache  │ ◀───────────▶ │   Worker     │
 └─────────────┘                │  src/index.js│
      ▲                         └──────┬───────┘
      │ serves the crowd               │ reads departures
      │ during spikes                  ▼
   visitors                      ┌──────────┐
                                 │ D1 SQLite│
                                 └──────────┘

/                  station picker
/{station}         departure board (HTML, edge cache 45s)
/vlak/{number}     trip route — full itinerary, passed vs upcoming
/api/stations      station list (cache 24h)
/api/board?s=ID    departures (JSON)
/api/nearest?lat=&lon=   nearest station
/ops               operational dashboard (Basic Auth)
/healthz           health check