hrrr-point-rs was marking fetch tasks 'done' with 0 profiles inserted
for ~13,900 historical contacts. The wgrib2 subprocess resamples HRRR
to the 0.125° CONUS prop grid, but the lookup keyed on the requested
point (rounded to 0.01° by Weather.round_to_hrrr_grid/2) — those keys
never match a 0.125° cell exactly, so every point fell through the
`cell.is_empty()` skip. Snap to the nearest 0.125° cell for lookup,
store at the original (lat, lon) so Weather.has_hrrr_profile?/3's
0.07° search window finds it on the next backfill tick.
TDD: added snap_key unit tests.