Function generate_report 

pub fn generate_report(
    graph: &KnowledgeGraph,
    communities: &HashMap<usize, Vec<String>>,
    cohesion_scores: &HashMap<usize, f64>,
    community_labels: &HashMap<usize, String>,
    god_nodes: &[Value],
    surprises: &[Value],
    detection_result: &Value,
    token_cost: &HashMap<String, usize>,
    root: &str,
    suggested_questions: Option<&[Value]>,
) -> String

Generate a comprehensive markdown analysis report.