Unify LiveLabs QA regression reporting

[Marco-03]

Summary

• Combines regression and PAR validation into one Jenkins workflow and report.
• Improves actionable findings, stable workshop destinations, masked PAR handling, retest workflow, and run status.
• Removes retired-workshop exclusions and the separate Fix List.
• Shows acknowledgement names only; generic LiveLabs help mailboxes are excluded.

Validation

• node --test scripts/reporters/root-summary-reporter.test.mjs