Function build

pub fn build(
    scanned: Vec<ScannedFile>,
    roots: Vec<String>,
    scanned_at: u64,
    chosen: &[Chosen],
) -> Catalog

Assembles the graph from the files that were read.

Processing order is deterministic — files are sorted by path first — so two scans of the same library produce exactly the same identifiers. Without that, neither a readable diff nor a reproducible test is possible.