Add Scene Warmup

Compile mounted content before its first reveal. Leaving the frustum does not itself discard a compiled pipeline. Warmup targets first-use compilation, not ongoing draw cost, asset downloads, or meshes that have not mounted yet.

Workflow

1. Read the target repository's instructions and inspect its dependencies, Canvas, renderer, render owner, and content/loading readiness. Check whether the hitch occurs on first entry but improves on revisiting the same content; repeated slow frames need profiling beyond warmup.
2. Confirm compatible React Three Fiber /webgpu APIs and a WebGPU renderer. The reference is tested with R3F 10.0.0-alpha.5 and Three 0.185.0; inspect installed APIs when versions differ. Its immediate visibility restoration relies on initialized Three collecting the render list synchronously before yielding. WebGL requires a different integration; do not transplant this WebGPU hook. A custom postprocessing pipeline is not required.
3. Call the get_component_reference tool from the threenix MCP server with { "slug": "scene-warmup" }. If the tool or authentication is unavailable, explain the access problem; do not reconstruct the reference from local or bundled sources.
4. Choose one destination root near the target scene. Write the returned files[] beneath it at each relative path: write utf-8 content verbatim and decode base64 content. Preserve paths; keep host integration edits outside the returned source.
5. Follow the returned integrationNotes and the integration contract below. Keep the host renderer, scene, camera, loading UI, and disposal ownership. Do not create a renderer or postprocessing pipeline just for warmup.
6. Install only returned dependencies absent from the target manifest, pinned to returned versions with the existing package manager. Preserve existing ranges; report incompatible installed APIs rather than silently upgrading the app.
7. Run the narrowest type-check/build and the runtime checks below. Report checks not performed and remaining hitch sources; a successful build alone does not demonstrate smoother frames.

Integration contract