NASA POWER (history) and MET Norway (forecast) carry no wind gusts, but gust is
a graded metric. This adds data/meteostat.py, which finds the nearest Meteostat
station to a cell and reads its daily peak gust (wpgt) from the keyless gzipped
bulk endpoints, filling the gust column on the NASA POWER history frame. Where no
station is within ~100 km it estimates from sustained wind (wind * GUST_FACTOR).
Bulk files (station list + per-station daily) are cached on disk so steady-state
network IO is near zero, and any lookup/fetch failure degrades to pure estimation
so a history fetch never fails. A constant estimate factor makes an estimated
gust redundant with wind, so real signal comes only where a station backs it.
Activates once NASA POWER becomes the primary history source; Open-Meteo already
carries its own gusts. New history_gust / meteostat_stations metrics phases map
to the meteostat source.
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