Red phase for the timeline date-label helper. Asserts delegation to the shared formatDocumentDate (localized DAY de/en, SEASON de, same-year RANGE) and the null cases for UNKNOWN/empty eventDate. The runtime mock path keeps the `.js` suffix so it matches the import under test. Refs #778 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>