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/scenes/project.js

@@ -261,6 +261,7 @@ export function normalizeShot(
       : {}),
     ...(rawShot?.dataPackIds ? { dataPackIds: [...rawShot.dataPackIds] } : {}),
     ...(rawShot?.move ? { move: deepClone(rawShot.move) } : {}),
+    ...(rawShot?.lens ? { lens: deepClone(rawShot.lens) } : {}),
     visual: {
       style: visual.style || 'normal',
       bloom: normalizeBloomState(bloom, {