feat(globe): dynamic lines on both engines

engine.lines.createLine({ id, widthPx, color, depthFailAlpha, dash
({ lengthPx, gapPx } | 'tactical'), arc ('none'|'geodesic'), modelMatrix,
pickId }) → a Line: setPositions (Cartesian3[] or a flat Float64Array),
setColor, setModelMatrix, show, destroy; lines.list() for QA. Options,
flat positions, geodesic densification (great circles of the geodetic
normals, height interpolated, one step per degree) and the registry are
engine-neutral (src/globe/lines.js); the fake engine keeps every line.

- Cesium: a Primitive of a PolylineGeometry (synchronous, rebuilt when
  the positions change) with a PolylineMaterialAppearance in an
  engine-owned collection; depthFailAlpha is depthFailAppearance with the
  alpha scaled; pixel dashes are PolylineDash (16-bit pattern); the
  tactical dash is the launches' selected-orbit shader under its own type
  (launches keep theirs until Task 15a moves them onto engine.lines).
- Navara: a public MeshDesc (transparent pass, unlit) holding a ribbon
  of one quad per segment, widened to CSS pixels in the vertex shader;
  a second copy drawn with GreaterDepth and the alpha scaled is the
  depth-fail part; dashes are cut in the fragment shader (pixels along
  the screen direction, or the tactical pattern over the fraction along
  the line); positions relative to the first point, the model matrix on
  the group. Geodesic arcs are densified on the CPU. Not pickable yet.
- The contract suite draws a three-point line on both engines: magenta
  along both segments, nothing off it, 1° east once turned by its model
  matrix, gone when hidden; a line 30 km under the ground shows only its
  depth-fail copy, dimmer than the line.

Main chunk 2,867,499 bytes (+7,197, +0.25 %: the Cesium lines).

scripts/format-scope.json

@@ -1074,5 +1074,8 @@
   "src/globe/navara/movers/pickIds.test.mjs",
   "src/globe/navara/movers/moverMesh.test.mjs",
   "src/globe/navara/movers/modelMover.test.mjs",
-  "src/bench/syntheticFlights.test.mjs"
+  "src/bench/syntheticFlights.test.mjs",
+  "src/globe/lines.test.mjs",
+  "src/globe/cesium/lines.test.mjs",
+  "src/globe/navara/lines/lineMesh.test.mjs"
 ]