feat(fleet): draw airport ground vehicles by callsign and ground stations as a radio mast

Feeds carry many airport ground vehicles (type ZVEH) and ground stations
(GRND) that were drawn as the generic plane, some at the 10 km airborne
default.

- types.json gains aircraft_callsign rules: a ZVEH callsign starting FIRE is
  a fire truck, PUSH/TUG a pushback tug, DEICER/SQUID/SQB a van, else a car.
  GRND draws a new 11.8 m radio mast (other/radio_mast.glb).
- resolveAircraft and aircraftModelSpec take the callsign; a matched rule
  names the model outright, ahead of the type's class model.
- The layer spec cache keys such types by the rule matched, so it holds at
  most one entry per rule.
- These models (catalog category `other`) draw at their built size, as such
  models already do, and a
  contact with no altitude whose model is one now stands on the ground; the
  feed's own type is kept for such contacts, as no airframe lookup knows it.
- Local ADS-B passes the callsign too.

scripts/package-boundaries.json

@@ -4815,7 +4815,9 @@
       "src/data/approxDistance.js",
       "src/data/renderAltitude.js",
       "src/data/aircraftClass.js",
-      "src/data/aircraftEmergency.js"
+      "src/data/aircraftEmergency.js",
+      "src/data/fleetModels.js",
+      "src/data/fleetTrailAnchors.js"
     ],
     "external": []
   },