Invert image order in beforeafter block preview

- Image "before" now displays on top (left side, clipped at 50%)
- Image "after" displays below (visible on right side)
- Update text block to support bullet lists
- Add heading fieldset to report blueprint

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

site/blueprints/pages/report.yml

@@ -47,6 +47,7 @@ tabs:
               - "1/2, 1/2"
             fieldsets:
               - text
+              - heading
               - image
               - beforeafter
       - width: 1/6