refactor(layers): W1 timestamps without JulianDate

Flights and military keep their fix history in plain milliseconds
(timeMs, whole ms as the Date the JulianDate came from held) and read
"now" from the app clock: the render-delay time, bracketing,
extrapolation, the warm-up check and the trail seed are number
arithmetic (motion.js, tracking.js, snapshotRenderer.js), as is the turn
rate and the forward synthetic fix in data/motionModel.js, which no
longer imports Cesium. The JulianDate scratch fields in state.js and the
unused JulianDate.now() in queries.js go. Launches (mission frame, panel,
selection), the tracked satellite's SGP4 epoch and the celestial ring's
sun and moon read the app clock; where a Cesium property still takes a
JulianDate it is built from the app clock's now (as JulianDate.now did
from Date.now). Wall-clock throttles and feed receipt stamps stay on
Date.now; property reads at viewer.clock.currentTime (render, frozen at
boot) move with the render code in the *a tasks.

Tests that built JulianDate history fixtures now build ms ones with the
same instants (motionModel.test, flights.test, militaryFlights.test); new
tests show the military delayed position and the tracked satellite follow
the app clock (both fail on the previous code).

src/layers/launches/rendering.js

@@ -1,4 +1,5 @@
 import * as Cesium from 'cesium';
+import { appClock } from '../../time/clock.js';
 import {
   TRAJECTORY_STAGE_COLORS,
   REPLAY_ORBIT_DURATION_SEC,
@@ -32,7 +33,11 @@ export function createRendering({
       return;
     }
     parts.panel.updateMissionTelemetry();
-    const time = Cesium.JulianDate.now(layerState._declutterTime);
+    // The app clock's now, as the JulianDate Cesium's entity properties take.
+    const time = Cesium.JulianDate.fromDate(
+      new Date(appClock.now()),
+      layerState._declutterTime,
+    );
     layerState._declutterOccluder.cameraPosition =
       layerState._viewer.scene.camera.positionWC;
     parts.overlays.updateReplayVehicleOverlay(layerState._declutterOccluder);