Event files can carry extra measurement tracks, and made-up Events use them #112

Parent

#27 (M6 General sensors)

Spec: docs/specs/general-sensors.md (added by PR #111; read it there until it merges). Parent: #27.

What to build

An Event file can hold optional measurement tracks (kind, unit, decimals, time/value points, one value for the whole Region, straight lines between points). A Sandbox Sensor whose NODE_MEASURES names a track sends it in its Community Reading. The made-up Events of both Regions gain air_temperature (°C), humidity (%) and wind_speed (m/s) tracks that fit their story. Ian and Bhote Koshi get none. Spec decisions 1 and 2.

Acceptance criteria

• A made-up Event plays and a Sandbox Sensor sends air_temperature, humidity and wind_speed in their wire units; /api/state holds them under that Node.
• The Ian and Bhote Koshi Events load unchanged and their Sensors send no new kinds.
• A Node with NODE_MEASURES naming a track sends it; one not naming it doesn't.
• An Event file with a bad track (flood kind repeated, another track's kind repeated, camera, times out of order, non-finite value) fails to load with a message naming the Event and the track.
• Flood Risk and Community Warnings are identical with and without the new tracks on the same Event.
• No Region file, Cache Pack or checked-in fixture changes.
• docs/specs/wire-formats.md lists the three new kinds and their wire units; scripts/check.sh node passes.

Blockers are native links.