First pass at C++ docs.

[Tod-Rive]

This is mostly Claude generated. I've made some changes to the output but this need a good once-over by someone familiar with the C++ API.

[Copilot]

Pull request overview

Adds an initial set of C++ runtime documentation pages to the docs site, covering core concepts (File/Artboard/Scene), rendering backends, the render loop, state machines/inputs, data binding, and asset loading, and wires them into the left-nav.

Changes:

• Added a new runtimes/cpp/ doc section with pages for getting started, rendering, state machines, data binding, asset loading, and external renderer integration.
• Documented the GPU RenderContext lifecycle (beginFrame/flush), resize handling, and fixed-timestep simulation guidance.
• Updated docs.json to expose the new C++ section in the “Runtimes” navigation.

Reviewed changes

Copilot reviewed 10 out of 12 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
runtimes/cpp/index.mdx	Adds C++ runtime overview page and entry-point links.
runtimes/cpp/getting-started.mdx	Adds build + first render-loop walkthrough.
runtimes/cpp/file-and-artboard.mdx	Adds file import, artboard querying/instancing, layout sizing, and lifetime guidance.
runtimes/cpp/state-machines.mdx	Adds scene lifecycle, pointer forwarding, input access, and state-change introspection.
runtimes/cpp/data-binding.mdx	Adds ViewModel runtime/instance/property usage docs and examples.
runtimes/cpp/asset-loading.mdx	Adds FileAssetLoader guidance with sync/async examples and caveats.
runtimes/cpp/rendering-loop.mdx	Adds detailed beginFrame/flush sequencing, frame descriptors, and operational notes.
runtimes/cpp/renderers.mdx	Adds per-backend RenderContext setup snippets (D3D11/12, Metal, Vulkan, GL/WebGL).
runtimes/cpp/external-renderer.mdx	Documents implementing Renderer/Factory to plug into custom backends.
docs.json	Adds the new C++ pages to the Runtimes sidebar nav.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 12 changed files in this pull request and generated 6 comments.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 12 changed files in this pull request and generated 4 comments.