feat(director): recorded camera tracks and shot lens (scene document v7)

Scene documents gain a second kind of explicit move: `move.track`, timed
samples of position, orientation and an optional 35 mm-equivalent focal
length. Playback, Load, Replay and seek share one sampler, which stretches
the recording to the shot's duration (so editing durationSec retimes a
take), takes the short arc for longitude/heading/roll and returns recorded
samples exactly. Tracks require the ellipsoid altitude reference and are
bounded to 10,000 samples.

Shots may also carry a `lens`: focal length and a thin-lens depth of field
whose distances are divided by a miniature scale, so a 1:1000 rig renders
the city like a tabletop model. A new camera-lens owner applies it to the
frustum and a depth-of-field post-process stage; shots without a lens
restore the default view. SceneDirector accepts the lens as an injected
dependency, captures a changed lens with a shot and gains addRecordedShot()
for takes. Versions 1-6 import unchanged.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_015H1iLusTzWpVKitGic2AW8

src/director/camera.test.mjs

@@ -73,7 +73,7 @@ test('v3 unversioned bloom already uses scale 2 and is not migrated again in lat
       }),
     ),
   );
-  assert.equal(project.version, 6);
+  assert.equal(project.version, 7);
   assert.equal(project.scenes[0].shots[0].visual.bloom.intensity, 50);
 });
 test('move endpoints, easing, shortest arcs and hold agree with scene seeking', () => {