Function compute_centrality 

pub fn compute_centrality(
    graph: &ArborGraph,
    iterations: usize,
    damping: f64,
) -> CentralityScores

Computes production-aware centrality scores for all nodes in the graph.

Uses a modified PageRank where:

1. Nodes initialize with equal score
2. Each iteration distributes scores along edges
3. Callers from test/spec/fixture files contribute 10x less weight — prevents test utilities from appearing more central than production code
4. Scores are normalized to [0.0, 1.0]

Arguments

• graph - The graph to analyze
• iterations - Number of iterations (10-20 is usually enough)
• damping - Damping factor (0.85 is standard)