Function generateCrossReferences

Auto-generate ArticleCrossReference objects for an article based on topic and actor overlap with existing index entries.

Strength is determined by total overlap (topics + actors):

• ≥3 shared items → strong
• 2 shared items → moderate
• 1 shared item → weak

Relationship is determined by date comparison:

• Target article is older (date < entry.date) → follows_up
• Target article is newer (date > entry.date) → preceded_by
• Target article has the same date → related