Function add_file 

pub fn add_file(
    graph: &mut CodeGraph,
    path: &str,
    language: &str,
) -> Result<NodeId>

Add a file node to the graph.

Creates a CodeFile node with path and language properties.

Arguments

• graph - The code graph to add the file to
• path - File path (e.g., “src/main.rs”)
• language - Programming language (e.g., “rust”, “python”)

Returns

The ID of the created file node.