The power_mw field represents the beacon's effective radiated power,
not just transmitter output. Relabel it as "TX power (EIRP)" on the
form and detail list, "EIRP (mW)" in the index, and drop the now-
meaningless tx_gain_dbi constant in RangeEstimate since the stored
value already includes antenna gain.
- 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.
