Live scene optics — WebGPU preview v5

Look through a spherical glass lens at actual, current Unity mesh geometry.
Moving a registered object, its animated bones, the lens or MainCamera changes
the refracted view every frame. No photograph or secondary camera is used.

Register objects that are already loaded:
await setOpticalObjects(["penguin", "backdrop"]);
await createOpticalLens("glass", 0, 4, 0, 1, 1.5, 1);

Move/change the lens: name, x, y, z, radius, refractive index, rays per pixel.
await setOpticalLens("glass", 0.3, 4, 0, 1, 1.5, 4);
await removeOpticalLens("glass");
var status = await getLiveOpticsState();

Use existing load() for CS objects, and wait until loading finishes before
registration. setOpticalObjects REPLACES the optical geometry selection; it
does not load, duplicate, freeze or change the physics of those objects.
Object position/rotation and animation continue through normal CS commands.
clearRun/clearCode/clearGPUInstances also remove optical lenses and registration.
Keep registration and lens setup in the saved editor code for restoration.

Quality: 1 or 4 primary rays per displayed lens pixel, selected by the last
argument. Each ray traces sphere entry/exit, reflection and transmission against
the registered geometry. Four averages subpixel samples and costs more GPU work.
Use a compact quality control and Apply button. Changing a slider only selects
the next value; Apply sends setOpticalLens. This is separate from the number of
visible diagram rays in drawOpticalRays. The live lens is display-resolution,
not the 128-pixel source-image demonstration. Material textures are resampled
to 256x256 at registration. No photographic source URL is required.

Current scope: perspective MainCamera outside the lens, spherical homogeneous
glass, Snell refraction, exact unpolarized Fresnel at boundaries and up to eight
internal reflections for TIR. Ordinary partial internal-reflection branches are
not accumulated; this is not a full light transport solver. No diffraction,
dispersion, caustic illumination or coupled multiple lenses. One lens per line
of sight. The lens is a visual surface, not a Rigidbody or collision object.

Registered opaque MeshFilter and SkinnedMeshRenderer geometry: up to32 named
roots,64 renderers,100000 triangles,64 materials. Static meshes must be readable;
unsupported geometry produces an error, never a screenshot fallback. Terrain,
particles and unregistered meshes are not traced. Misses use ambient lighting.
Shading uses base color/texture, the main directional light and ambient SH;
not all URP material effects, shadows, transparency or normal maps are reproduced.
GPU traverses triangle BVHs and shades rays; CPU supplies current transforms.
Skinned meshes are baked/refitted on CPU each frame, so this is not CPU-free.
Inspect performance with the actual registered models before increasing quality.

For a live lens experiment use these v5 functions. The older renderOpticalImage
and viewOpticalImage take a FLAT SOURCE PICTURE and are separate diagnostic/
projection tools. Do not substitute them for looking at a live Unity object.
Capturing the live result or projecting it onto a measurement screen is a useful
additional output; a general live-geometry screen projection is not yet exposed.