Attention refactor, better categorization and explanation

Improve explanations: optimize head categorization and comparison thresholds, enhance ablation explanation, rewrite all tooltips for high school level

Refactor: Move attention head categorization to on-demand per-layer display - Removed automatic Attention Head Categorization section from main panel - Created categorize_single_layer_heads() for per-layer categorization - Updated run_analysis to skip automatic head categorization - Enhanced node click callback to show layer-specific categorization - Analysis Results section now displays both BertViz and categorized heads on node click

Feature 5: Implement attention head detection and categorization with visual display