Function exit_code 

pub fn exit_code(summary: &ReportSummary, threshold: &Severity) -> i32

Returns a UNIX-style exit code appropriate for CI pipelines.

Condition	Code
No findings at or above threshold	0
At least one finding at or above threshold	1
Scanner errors occurred (regardless of finds)	2

Callers may OR the codes together; e.g. code 3 = findings + errors.