Implement clear, non-technical feedback system for validation results (sub-task 6.7)

- Created FeedbackSystem with user-friendly explanations and suggestions
- Added categorization of issues into readable groups (Readability, Structure, Grammar, etc.)
- Implemented personalized feedback based on user experience level and preferences
- Created comprehensive UserFriendlyFeedback with overall summaries and actionable steps
- Added progress tracking with achievements, milestones, and score history
- Implemented learning opportunities and improvement suggestions
- Created batch feedback analysis for content portfolios
- Added markdown and JSON export capabilities for feedback reports
- Integrated with smart configuration system for personalized experience
- Provided clear priority levels and estimated fix times for each issue group

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: michael-borck