Variable: RenderBackends
constRenderBackends:RenderBackendConstants
Runtime render backend constants: built-in names map to wire-type strings.
Built-ins are available immediately. Extension backends are added when you
call registerRenderBackend({ name: 'WEBGPU', backend: 'myOrg:webgpu', ... }).
For compile-time names, augment RenderBackendConstants only —
Enums.RenderBackends is typed from it.