Function compile_batch 

pub fn compile_batch(
    batch: &[PathBuf],
    content_dir: &Path,
    build_dir: &Path,
    site_dir: &Path,
    template_dir: &Path,
    batch_idx: usize,
) -> Result<()>

Compiles a single batch of content files into the build directory.

Creates a temporary content directory containing only the batch files, runs staticdatagen::compile on it, then merges the output into the final site directory.