Command Palette → Create 3D Object: Add the missing Ellipsoid and Compass primitives + Transparency input for all primitives

[zxq82lm]

• The “Create 3D Object” palette still exposes only the basic primitives (GLTF, Sphere, Cylinder, Cuboid, Plane); the ellipsoid variant and our built‑in compass mesh never show up there, so they can’t be spawned from the command palette even though the schematic loader and inspector already support them.
• It would also be worth adding a transparency input across all primitives (defaulting to mid-opacity?), so users can dial in alpha without editing the object later.