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.

docs/CURRENT-STATE.md

@@ -7429,7 +7429,7 @@ pins and share links already supply complete boxes.
   normal four-samples-per-250-ms budget. Retry timestamps more than the maximum
   30-second backoff ahead of the current clock are ignored. A smaller rollback
   can retain a bounded retry delay of up to 30 seconds.
-- Commercial and military aircraft use the same high-level FLEET model regime: 2D billboards when zoomed out, optional glTF models when closer, controlled by the DISPLAY rail `3D` toggle and `Proximity` / `All` modes. Every model is one of the project's procedural fleet models (`public/models/fleet/`, MIT, 121 GLBs, about 2 MB in all; `public/models/README.md`), chosen per aircraft by `aircraftModelSpec` (`src/data/fleetModels.js`): its ICAO type's entry in `types.json`, else the model of its `classifyAircraft` class for a type the map lacks, else its ADS-B emitter category's, else the default airliner. It is drawn LIFE SIZE: the type's published length over the model's built length (`src/layers/flights/modelSpec.js`, shared by Flights, Military Flights and Local ADS-B), and a grounded aircraft stands the model's scaled clearance above the ground. `classifyAircraft` still picks the 2D icons. The whole set loads once, up front, when a layer that draws it starts (`loadFleetModelSet`, which logs `[Fleet] N/121 models (X MB) loaded in N ms`); models are built from those bytes, never fetched mid-session, and an aircraft stays its billboard until the set has loaded. Textured civilians carry a HEAVY tint, not a light one: `MODEL_COLOR_BLEND_AMOUNT` is `0.94` in BOTH layers under Cesium's `ColorBlendMode.MIX`, so the class colour supplies 94% of the surface and the model's own vertex colour ~6%; military models are flat amber, or emergency red. IR boost raises the blend to a full `1.0`. Under NVG/FLIR (map preset or Cockpit vision) models render unlit flat-white at full alpha and scene fog is disabled (fog otherwise blacks out distant models with the globe hidden); state restores on exit.
+- Commercial and military aircraft use the same high-level FLEET model regime: 2D billboards when zoomed out, optional glTF models when closer, controlled by the DISPLAY rail `3D` toggle and `Proximity` / `All` modes. Every model is one of the project's procedural fleet models (`public/models/fleet/`, MIT, 122 GLBs, about 2 MB in all; `public/models/README.md`), chosen per aircraft by `aircraftModelSpec` (`src/data/fleetModels.js`): the first of its ICAO type's callsign rules in `types.json` (`aircraft_callsign`) its callsign matches, else its type's entry, else the model of its `classifyAircraft` class for a type the map lacks, else its ADS-B emitter category's, else the default airliner. It is drawn LIFE SIZE: the type's published length over the model's built length (`src/layers/flights/modelSpec.js`, shared by Flights, Military Flights and Local ADS-B), and a grounded aircraft stands the model's scaled clearance above the ground. An airport ground vehicle (feed type `ZVEH`) is a fire truck (`FIRE…`), pushback tug (`PUSH…`, `TUG…`), van (`DEICER…`, `SQUID…`, `SQB…`) or else a car by its callsign, and a ground station (`GRND`) is an 11.8 m radio mast; these models (catalog category `other`) are drawn at their built size, and such a contact with no altitude stands on the ground instead of at the airborne default (`src/layers/flights/records.js`). `classifyAircraft` still picks the 2D icons. The whole set loads once, up front, when a layer that draws it starts (`loadFleetModelSet`, which logs `[Fleet] N/122 models (X MB) loaded in N ms`); models are built from those bytes, never fetched mid-session, and an aircraft stays its billboard until the set has loaded. Textured civilians carry a HEAVY tint, not a light one: `MODEL_COLOR_BLEND_AMOUNT` is `0.94` in BOTH layers under Cesium's `ColorBlendMode.MIX`, so the class colour supplies 94% of the surface and the model's own vertex colour ~6%; military models are flat amber, or emergency red. IR boost raises the blend to a full `1.0`. Under NVG/FLIR (map preset or Cockpit vision) models render unlit flat-white at full alpha and scene fog is disabled (fog otherwise blacks out distant models with the globe hidden); state restores on exit.
 - Vessels, Transit and Rail draw fleet models under the same DISPLAY rail `3D` toggle, at the same altitude ceiling, caps and add/keep radii as the aircraft (`FLEET_MODEL_POLICY`, `src/layers/flights/policy.js`; `createFleetModelLayer`, `src/data/fleetModelInstances.js`). A vessel's model follows its AIS ship type and is drawn at its reported length and beam (AIS static dimensions A+B and C+D, now carried on vessel rows as `length` and `beam`), standing at the sea surface, heading by true heading then course. A transit vehicle's model follows its layer mode (bus, tram, subway, rail or ferry; a vehicle of `unknown` mode keeps its icon), a train's its rail category and mode (rail, metro or tram). Neither the transit nor the rail sources carry a GTFS `route_type` or a finer mode (monorail, gondola, funicular, cable car), so the set's models for those and their `transit.elevation` lifts are not reached by any live source today. Both stand on the road or rail top they are drawn on, without the 1.5 m `GROUND_FLOOR_LIFT_M` their icons carry, and are painted in their mode or category colour where the model's `_TINT` attribute marks it. A vessel model is clipped at its waterline (one clipping plane per model, at the model origin's horizontal plane), so its hull below the water never shows through a plain globe, which Cesium does not depth-test models against. Under the NVG/FLIR styles (the Flights `irBoost` parameter) these models render unlit flat white, as aircraft models do. Each vehicle's icon stays the visual until its model is loaded, ready and placed; a model is picked as its icon is, and a vehicle drawn as its model keeps its selection card and its place in the detection overlay.
 - **Aircraft models skip Cesium's dynamic environment map (2026-10-24).** Flights, Military Flights and Local ADS-B pass `environmentMapOptions: AIRCRAFT_ENVIRONMENT_MAP_OPTIONS` (`{ enabled: false }`, `src/data/aircraftModelLighting.js`) to every drawn model. Otherwise each `Model` renders the sky around it and reads it back from the GPU (`readPixels`) when it is first placed, and again whenever it moves more than 1 km, the scene's atmosphere settings change, or (under sunlight dynamic lighting) an hour of scene time passes (`DynamicEnvironmentMapManager`, Cesium 1.138). With the class colour supplying 94% of the surface, the models are lit from Cesium's default spherical harmonics instead, with no specular environment map, so the sky's model-lighting cube map no longer reaches aircraft. `src/data/aircraftModelLighting.test.mjs` pins the option at every drawn model call; every model is built from the fleet set loaded up front, so there is no separate preload.
 - The DISPLAY-rail `3D` toggle is the user-facing activation path for both aircraft layers. Their small approved GLBs build their render resources without Cesium's frame-spread job queue, preventing continuous Photorealistic 3D Tiles streaming from starving model readiness; model caps, tracking, camera, and fallback billboards are unchanged.