Function force_load_block_light_chunk 

pub fn force_load_block_light_chunk(
    workset: &LightWorkset,
) -> Result<BlockLightUpdateResult, BlockLightPropagationContextError>

Force-synchronizes block-light sections for an already-lit loaded chunk.

This matches the block layer of ScalableLux forceLoadInChunk: existing light data is kept, empty-section state is synchronized, and dirty visible sections are published before the later edge-check pass.