fix(camera): keep a deferred recovery check through long holds

A Director hold longer than the settle check's five-minute bound used
to expire the deferred check, so a run that ended on a stars-only shot
after a long hold stayed there until the next move. While a flight or a
playing scene defers the check, its bound no longer counts down; the
flight or scene bounds the deferral itself.

Also correct the trackball note in CURRENT-STATE: Cesium's tilt tests
the screen centre, so any tilt (drag or touch) with the centre on the
stars between 1,000 and 7,500 km now tilts about the planet's edge or
does nothing, wherever it starts. Rotation drags that start on the
planet are unchanged.

src/app/application.test.mjs

@@ -765,6 +765,8 @@ test('a check a scene or flight defers runs once it ends', () => {
     // A hold on a stars-only shot: quiet, with or without Cesium's moveEnd.
     for (let i = 0; i < 4; i += 1) timers.tick();
     if (viaMoveEnd) camera.moveEnd.raiseEvent();
+    // Longer than the settle check's five-minute bound.
+    for (let i = 0; i < 1500; i += 1) timers.tick();
     assert.equal(globeOutOfFrame(camera), true, 'left alone while it plays');
     assert.equal(timers.pending(), 1, 'still watching');
     playing = false;

src/app/viewer.js

@@ -174,7 +174,7 @@ const SETTLE_GIVE_UP_MS = 5 * 60_000;
  * Heading and position are kept. Tracked cameras, locked ones (non-identity
  * transform), a camera flight in progress, the 2D and Columbus modes, and any
  * time `paused` returns true (an authored scene playing) are left alone; a
- * check they defer runs again once they end, within the settle check's bound.
+ * check they defer runs once they end, however long they last.
  * `keyholeRadius`
  * returns the radius of the visible circle when a scope mask hides the rest of
  * the frame (see `globeFrameShare`), or 0; it is read at every check.
@@ -261,8 +261,11 @@ export function installGlobeInViewRecovery(
     }
     // Two quiet samples in a row after a move: at rest for half a second, as
     // for moveEnd.
-    if (restingSamples >= 2 && movedSinceCheck && recover())
-      movedSinceCheck = false;
+    if (restingSamples >= 2 && movedSinceCheck) {
+      if (recover()) movedSinceCheck = false;
+      // A flight or a playing scene bounds its own deferral.
+      else settleElapsed = 0;
+    }
     if (settleElapsed >= SETTLE_GIVE_UP_MS) return;
     Cesium.Cartesian3.clone(camera.positionWC, lastPosition);
     Cesium.Cartesian3.clone(camera.directionWC, lastDirection);