#253 God Class Anti-Pattern in ScraperErrorHandler

[Aditya8369]

Refactoring Complete - God Class Anti-Pattern Resolved

What Was Accomplished:
Successfully split the monolithic ScraperErrorHandler class into 4 focused classes:

• ErrorClassifier - Handles error type detection (network, rate limit, auth, parsing, etc.)
• RetryManager - Manages retry logic with exponential backoff
• ScraperResponseBuilder - Creates standardized responses and handles validation
• ScraperMetricsLogger - Handles performance logging and metrics collection

Key Improvements:

• Reduced code complexity: Main class went from ~400 lines to ~100 lines
• Single Responsibility: Each class now has one clear purpose
• Better testability: Smaller, focused classes are easier to unit test
• Zero breaking changes: Same public API maintained
• Improved maintainability: Changes to one concern don't affect others

Testing Results:

• Error handling tests passed - Core functionality verified
• No breaking changes - Existing code continues to work

Files Created/Modified:

• backend/src/utils/errorClassifier.js (new)
• backend/src/utils/retryManager.js (new)
• backend/src/utils/scraperResponseBuilder.js (new)
• backend/src/utils/scraperMetricsLogger.js (new)
• backend/src/utils/scraperErrorHandler.js (refactored)
• TODO.md (updated with completion status)

fixes #253

[Aditya8369]

@Yugenjr assign under ecwoc