Update legend text for better accuracy

Changed legend descriptions to be more precise:
- "Model A better" → "Model A better than avg"
- "= Avg delta" → "Equal to avg"
- "Model B better" → "Model A worse than avg"

This clarifies that colors represent Model A's performance relative
to the average delta, not a direct comparison between models.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

visualization/html_generator.py

@@ -663,15 +663,15 @@ def generate_comparison_html(
         <div class="legend">
             <div class="legend-item">
                 <div class="legend-box" style="background-color: rgb(77, 255, 77)"></div>
-                <span>Model A better</span>
+                <span>Model A better than avg</span>
             </div>
             <div class="legend-item">
                 <div class="legend-box" style="background-color: rgb(255, 255, 255)"></div>
-                <span>= Avg delta</span>
+                <span>Equal to avg</span>
             </div>
             <div class="legend-item">
                 <div class="legend-box" style="background-color: rgb(255, 77, 77)"></div>
-                <span>Model B better</span>
+                <span>Model A worse than avg</span>
             </div>
             <div class="legend-item" style="margin-left: 20px;">
                 <span style="color: #aaa;">Saturation:</span>