Function process_content 

pub fn process_content(
    config: &DocsConfig,
    config_dir: &Path,
    highlighter: &Highlighter,
    head_injection: &str,
) -> Result<Vec<PageDescriptor>>

Process all content files and return page descriptors.

config_dir is the directory containing config.json; relative paths declared in the config (such as a custom page’s stateFile) are resolved against it.

head_injection is the fully-resolved <head> snippet (CSS link tags + config.head entries). It MUST be computed before this call so the descriptor is render-ready.