Adds Microwaveprop.Propagation.AsosNudge: a pure IDW bias-field module
that takes ASOS observations + HRRR profiles and returns re-scored grid
rows for every cell within 250km of a reporting station. Upper-air
fields (min_refractivity_gradient, pwat_mm, hpbl_m, profile, duct
metadata) pass through unchanged so HRRR's signal isn't clobbered.
The old AsosAdjustmentWorker was unwired and buggy — nil'd out ~22% of
the scoring weight and wrote orphan timestamps. Replaced with a slim
worker that queries the latest HRRR valid_time, fetches live ASOS
currents, calls AsosNudge.compute/3, and upserts onto
(lat, lon, valid_time, band_mhz) so nudged values overwrite the HRRR
hour cleanly instead of polluting available_valid_times. After each
upsert it warms ScoreCache and broadcasts propagation:updated so live
/map clients refresh.
Cron hooked up every 10 minutes in config.exs and dev.exs. Also cleaned
up the stale "dev has propagation disabled" note in CLAUDE.md.
13 new AsosNudge unit tests cover: residual computation (co-located,
out-of-grid, nil fields), IDW weighting (single station, far station,
two equidistant stations, nil component handling), upper-air
preservation, and the compute/3 entry point's shape and radius filter.
Drive-by Styler formatting touched a handful of unrelated files from
`mix format`.
