Function propagate_block_light_changes 

pub fn propagate_block_light_changes(
    workset: &LightWorkset,
    positions: impl IntoIterator<Item = BlockPos>,
) -> Result<BlockLightUpdateResult, BlockLightPropagationContextError>

Runs ScalableLux-style block-light propagation for changed blocks in a scoped workset.

This is the block-light equivalent of ScalableLux propagateBlockChanges plus publishing edited sections. It assumes the caller already created a cache window around the affected chunk and will deliver returned section updates to the world/chunk notification layer.