Function render_junit_for_receipt 

pub fn render_junit_for_receipt(receipt: &CheckReceipt) -> String

Renders a CheckReceipt as a JUnit XML report.

The structure is:

• <testsuites> - root element, one per receipt
• <testsuite> - one per unique rule_id
• <testcase> - one per finding
• <failure> - present for error/warn severity findings