Add automated validation for risk ID consistency

[Sven-NOM]

Add automated validation for risk ID consistency

Description
Several of the issues above could be caught automatically. Consider adding a validation step to ensure:
• Risk labels match their anchors.
• No duplicated risks appear unintentionally.
• All referenced risk IDs exist in the risk table.

Expected outcome
• A linting or build-time check that fails on invalid or duplicated risk references.

[Sven-NOM]

Automated validation (#133)

• Added .github/workflows/validate-risk-refs.yml
• Added scripts/validate-risk-refs.sh
• Checks: label/link matches, no duplicates, all referenced risks exist

This seems to work fine now:

Validation workflow output

The GitHub Action validate-risk-refs workflow ran successfully:

=== Checking label/link mismatches ===
OK: All labels match their links

=== Checking for duplicate risks in same list ===
OK: No duplicate risks found in any list

=== Checking for non-existent risk references ===
OK: All referenced risks exist in the risk table

=== Summary ===
PASSED: All risk reference checks passed