- GefsClient.build_profile/1: converts raw wgrib2 output into the
scorer-shaped profile, deriving Td from RH via Magnus at both the
surface and each pressure level
- GefsClient.fetch_grid_profiles/3: downloads the idx sidecar from
NOMADS, byte-ranges only the surface messages, hands the slim
GRIB2 binary to wgrib2 -lola for bilinear regridding from 0.5°
onto the CONUS 0.125° grid
- GefsFetchWorker: one Oban job per (run_time, forecast_hour),
upserts into gefs_profiles and runs SoundingParams.derive so the
same refractivity/ducting metrics flow through
Oban gets a new :gefs queue (2 slots dev/config, 1 slot per prod
pod). Test env gets a gefs_req_options Req.Test stub slot so future
integration tests can drive the full fetch path. No cron wiring or
scorer integration yet — that's Step 3.