fix(director): turn heading and roll the short way for any authored angle

A single % made the seek delta negative when the target angle was more than
540° below the start, so 350° to -350° turned 340° through 180°. Uses the
same double modulo as playback, and adds tests for exact ±180° endpoints and
a near-antipodal seek.

src/director/director-dateline-seek.test.mjs

@@ -24,3 +24,30 @@ test('director seek follows the short dateline arc in both directions', () => {
   }
   assert.equal(cameraAtProgress(camera(20), camera(24), 0.5).lon, 22);
 });
+
+test('director seek keeps exact ±180 endpoints and picks the short arc near the antipode', () => {
+  for (const [a, b] of [
+    [180, -180],
+    [-180, 180],
+  ]) {
+    assert.equal(cameraAtProgress(camera(a), camera(b), 0).lon, a);
+    assert.equal(cameraAtProgress(camera(a), camera(b), 1).lon, b);
+    assert.equal(
+      Math.abs(cameraAtProgress(camera(a), camera(b), 0.5).lon),
+      180,
+    );
+  }
+  // 10°E to 169.9°W is 179.9° westward through Greenwich, not 180.1° east.
+  const mid = cameraAtProgress(camera(10), camera(-169.9), 0.5).lon;
+  assert.ok(mid > -81 && mid < -79, `short arc midpoint, got ${mid}`);
+});
+
+test('director seek turns heading and roll the short way for any authored angles', () => {
+  const pose = (heading, roll) => ({ ...camera(0), heading, roll });
+  const mid = cameraAtProgress(pose(350, 350), pose(-350, -350), 0.5);
+  // 350° and -350° are 20° apart through 0°/360°, not 340° through 180°.
+  for (const value of [mid.heading, mid.roll]) {
+    const wrapped = ((value % 360) + 360) % 360;
+    assert.ok(wrapped < 1e-9 || 360 - wrapped < 1e-9, `got ${value}`);
+  }
+});

src/director/timeline.js

@@ -41,7 +41,9 @@ export function cameraAtProgress(fromCamera, toCamera, progress) {
   const lerp = (from, to) => Number(from) + (Number(to) - Number(from)) * eased;
   const lerpAngle = (from, to) => {
     const start = Number(from) || 0;
-    const delta = ((Number(to) - start + 540) % 360) - 180;
+    // Double modulo keeps the delta in [-180, 180) for any authored angles,
+    // as sampleCameraMove does; a single % goes negative below -540.
+    const delta = ((((Number(to) - start + 540) % 360) + 360) % 360) - 180;
     return start + delta * eased;
   };
   return {