Three improvements to the contact detail page:
* Track async hydration per source in `hydration_pending` so the
Terrain / Soundings / Atmospheric Profile sections render a loading
spinner while their task is in-flight instead of briefly flashing
"no data available" before the payload arrives.
* Propagation analysis summary now names the origin station by
callsign ("Path is terrain-obstructed at N mi from W5XD") instead
of the generic "station 1" placeholder.
* Elevation profile chart labels the 0-mi and max-mi ticks with the
matching callsign so it's obvious which end of the profile is
which station.
Graham McIntire
5488744f44