- Add on_the_air boolean to beacons (default true); surfaced as a
checkbox on the form, a badge on the index, and in the detail list.
- Render a Leaflet map on the beacon show page with a marker at the
beacon's lat/lon tooltipped with callsign + frequency. Marker is
green when on air, gray when off.
- Compute and draw a reception-range estimate as concentric signal-
strength rings. New Microwaveprop.Beacons.RangeEstimate solves a
link budget (FSPL + O2/H2O absorption from BandConfig) at five RX
thresholds (-100 to -145 dBm), then scales by 0.5 + score/100 from
the latest Propagation.point_detail at the beacon's grid square, so
current HRRR conditions shift the rings in or out.
- Re-enable the hourly PropagationGridWorker cron and freshness
monitor in dev.exs so dev actually has HRRR-backed scores to feed
the new estimator.