Remove unused _unusedExtractTags function

- Function was kept for backward compatibility but is never used
- Removing it to fix TypeScript warning
- All TypeScript checks now pass

lib/nostrEventParsing.ts

@@ -84,14 +84,6 @@ export function parseReviewFromEvent(event: Event): Review | null {
   }
 }
 
-// extractTags is now replaced by extractTagsFromEvent from nostrTagSystem
-// This function is kept for backward compatibility but should be migrated
-// Currently unused - kept for potential future migration
-function _unusedExtractTags(_event: Event) {
-  // This function is intentionally unused - kept for backward compatibility
-  // If needed in the future, uncomment and implement using _event parameter
-  return null
-}
 
 function getPreviewContent(content: string, previewTag?: string) {
   const lines = content.split('\n')