Live Caltrans roadside camera snapshots near a point or on a route.

Data: ~3,000 in-service Caltrans cameras statewide. Every returned
image_url was verified live moments ago (offline cameras that serve a
placeholder frame are filtered out), so images can be shown directly.
Snapshots refresh roughly every minute; stream_url (when present) is
an HLS video stream.

Filters: center "lat,lon" (required unless route is given) with
radius_km; route (e.g. "I-80", "50") narrows to that highway. Results
sort nearest-first when a center is given. Use a camera to let the
user SEE conditions: fog on the pass, snow on the pavement, traffic
density at an interchange.