v2.1.0 - Improve helper functions and docs

Changelog

2.1.0

• Helpers (formerly dedupe): normalizeComment now strips HTML by default and supports optional stripPunctuation; isValidComment returns a ValidationResult with valid and issues instead of a boolean, checking for empty, too short, all caps, excessive repeats, and no alphabetic characters.
• Sentiment: analyzeSentiment now uses the sentiment package (AFINN-165) directly—no callback required. Returns score, comparative, and label.