DrawableResourcesHolder
Resolves the plain string name the Image tile's resourceName field references to an actual app-bundled DrawableResource — the mechanism behind Image (as opposed to AsyncImage, which loads from a URL/bytes and doesn't need this holder). A single Koin single, built once at startup from MosaicDependencyInjectionConfig.drawableResources.
Parameters
resources
every registered name → drawable mapping, supplied by the app host.