Function parse_build_number 

pub(crate) fn parse_build_number(output: &str) -> Option<u32>

Extract the llama.cpp build number from a --version banner.

Reads two shapes, in order:

Shape	Example	Source
version: <n>	version: 9656 (a1b2c3d)	llama-server’s own banner
b<n> token	llama-b10327-bin-linux	release tag in a path or banner

Returns None rather than a guess when neither appears — see the module docs on why an unparsed runtime must not look like a featureless one.