fix(vessels, transit, rail): fleet models keep their cards and detection, stand on the floor, clip ships at the waterline and follow NVG/FLIR

- a vehicle drawn as a model keeps its selected card and stays in the detection overlay
- transit and rail models drop the 1.5 m floor lift their icons carry
- vessel models are clipped below the waterline
- models switch to an unlit white look under NVG/FLIR and back
- unknown transit modes keep their icon
- aircraft model specs are cached per set; no key-array copies per frame

src/data/modelScale.test.mjs

@@ -288,3 +288,11 @@ test('civilian and military globe-view aircraft retain the established 3.0 near
     );
   }
 });
+
+test('a layer asking every tick gets one cached spec per type and category', async () => {
+  const { aircraftLayerModelSpec } = await import('../layers/flights/modelSpec.js');
+  const a = aircraftLayerModelSpec({ typeCode: 'A320' }, set);
+  assert.equal(aircraftLayerModelSpec({ typeCode: 'A320' }, set), a);
+  assert.notEqual(aircraftLayerModelSpec({ typeCode: 'B744' }, set), a);
+  assert.ok(Object.isFrozen(a));
+});