Function file_to_source_item 

fn file_to_source_item(
    path: &Path,
    relative_path: &str,
    repo_dir: &Path,
    repo_url: &str,
    head_sha: &str,
    source: &str,
) -> Result<SourceItem>

Convert a file in the cloned repo to a SourceItem.

Extracts Git metadata (commit timestamp, author) and generates a web-browsable URL for GitHub/GitLab repositories.