WebGPU RT: wavefront tracer core (GENERATE/PREP/TRACE/SHADE/RESOLVE)

Replace the megakernel @compute entry with five wavefront kernels sharing
one module, connected by GPU ray/hit/payload buffers and a GPU-driven
indirect bounce loop:

  GENERATE -> (PREP -> TRACE -> SHADE) x maxDepth -> RESOLVE

- TRACE contains zero user code (pure _rtwTraverseTlas/Blas, opaque-only).
- PREP publishes dispatchWorkgroupsIndirect args from the live ray count;
  the indirect-args buffer lives in its own bind group so it is never
  bound read-write in the same dispatch that consumes it as INDIRECT.
- New emit/accumulate API: rtEmitPrimaryRay / rtEmitRay / rtAccumulate,
  plus an optional user Resolve stage (tonemap hook; identity by default).
- Per-pass WfParams via a dynamic-offset uniform ring (curIsA/bounce vary
  between passes within one submit).
- Payload-typed wfPayload binding emitted in the codegen region after the
  user's struct Payload; payload travels with each ray (2*W*H slots).
- Request maxBufferSize / maxStorageBufferBindingSize / maxComputeWorkgroups
  PerDimension so the W*H-sized work buffers fit past the 128MB baseline.

VulkanTriangle ported to the new API and renders bit-identical to the
megakernel baseline at maxDepth=1.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

interfaces/Crafter.Graphics-ShaderBindingTableWebGPU.cppm

@@ -18,6 +18,11 @@ export namespace Crafter {
         Miss       = 1,
         ClosestHit = 2,
         AnyHit     = 3,
+        // Wavefront RESOLVE-stage tonemap/output hook. Optional: if no
+        // Resolve shader is registered, RESOLVE writes the linear accum
+        // buffer through unchanged. Signature:
+        //   fn <entryFn>(coord: vec2<u32>, hdr: vec4<f32>) -> vec4<f32>
+        Resolve    = 4,
     };
 
     // One WGSL shader source + the function name PipelineRTWebGPU should