Fix #79: Add JD keyword extraction and normalize resume scoring

[omrjadhav]

This PR addresses Issue #79 by enhancing the resume scoring system to dynamically use keywords from the job description.

• Increased keyword extraction limit from 15 → 20 to capture a broader set of relevant skills and terms.
• Updated scorer.py to use extracted keywords for scoring instead of static lists.
• Enhanced error handling for all scoring components (keywords, formatting, sentence structure, length).
• Normalized final scoring to provide a balanced evaluation.