Refactor and document FrogAnalyzer for FROG image analysis

Improved docstrings and comments throughout frog_analysis.py for clarity and maintainability. Refactored FrogAnalyzer class to enhance parameter documentation, error handling, and code structure. Added detailed explanations for methods, clarified return types, and improved logging. No functional changes to analysis logic; changes are focused on readability and developer usability.

Author: skbarber