Function scoreCandidate

Score candidate against queryWords. Returns 0 when no match. Higher = better match.

The exact rules:

• Exact name match on a single-word query: 100
• Whole-name AND-narrow on lowercased name: 50
• Word-of-name AND-narrow: 40
• Keywords AND-narrow (all matched): 25
• Partial keyword match: 10 × matched-count
• Partial name-word match: 5 × matched-count