refactor(admin): Migrate AdminAjaxHandler to Clean Architecture

- Move AdminAjaxHandler to Admin/Shared/Infrastructure/Api/Wordpress/
- Create FieldMapperInterface for decentralized field mapping
- Create FieldMapperRegistry for module discovery
- Create FieldMapperProvider for auto-registration of 12 mappers
- Add FieldMappers for all components:
  - ContactFormFieldMapper (46 fields)
  - CtaBoxSidebarFieldMapper (32 fields)
  - CtaLetsTalkFieldMapper
  - CtaPostFieldMapper
  - FeaturedImageFieldMapper (15 fields)
  - FooterFieldMapper (31 fields)
  - HeroFieldMapper
  - NavbarFieldMapper
  - RelatedPostFieldMapper (34 fields)
  - SocialShareFieldMapper
  - TableOfContentsFieldMapper
  - TopNotificationBarFieldMapper (17 fields)
- Update functions.php bootstrap with FieldMapperProvider
- AdminAjaxHandler reduced from ~700 to 145 lines
- Follows SRP, OCP, DIP principles

BACKUP BEFORE: Removing CTA A/B Testing legacy system

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

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

Admin/TableOfContents/Infrastructure/FieldMapping/TableOfContentsFieldMapper.php

@@ -0,0 +1,85 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Admin\TableOfContents\Infrastructure\FieldMapping;
+
+use ROITheme\Admin\Shared\Domain\Contracts\FieldMapperInterface;
+
+/**
+ * Field Mapper para Table of Contents
+ *
+ * RESPONSABILIDAD:
+ * - Mapear field IDs del formulario a atributos de BD
+ * - Solo conoce sus propios campos (modularidad)
+ */
+final class TableOfContentsFieldMapper implements FieldMapperInterface
+{
+    public function getComponentName(): string
+    {
+        return 'table-of-contents';
+    }
+
+    public function getFieldMapping(): array
+    {
+        return [
+            // Visibility
+            'tocEnabled' => ['group' => 'visibility', 'attribute' => 'is_enabled'],
+            'tocShowOnDesktop' => ['group' => 'visibility', 'attribute' => 'show_on_desktop'],
+            'tocShowOnMobile' => ['group' => 'visibility', 'attribute' => 'show_on_mobile'],
+            'tocShowOnPages' => ['group' => 'visibility', 'attribute' => 'show_on_pages'],
+
+            // Content
+            'tocTitle' => ['group' => 'content', 'attribute' => 'title'],
+            'tocAutoGenerate' => ['group' => 'content', 'attribute' => 'auto_generate'],
+            'tocHeadingLevels' => ['group' => 'content', 'attribute' => 'heading_levels'],
+            'tocSmoothScroll' => ['group' => 'content', 'attribute' => 'smooth_scroll'],
+
+            // Typography
+            'tocTitleFontSize' => ['group' => 'typography', 'attribute' => 'title_font_size'],
+            'tocTitleFontWeight' => ['group' => 'typography', 'attribute' => 'title_font_weight'],
+            'tocLinkFontSize' => ['group' => 'typography', 'attribute' => 'link_font_size'],
+            'tocLinkLineHeight' => ['group' => 'typography', 'attribute' => 'link_line_height'],
+            'tocLevelThreeFontSize' => ['group' => 'typography', 'attribute' => 'level_three_font_size'],
+            'tocLevelFourFontSize' => ['group' => 'typography', 'attribute' => 'level_four_font_size'],
+
+            // Colors
+            'tocBackgroundColor' => ['group' => 'colors', 'attribute' => 'background_color'],
+            'tocBorderColor' => ['group' => 'colors', 'attribute' => 'border_color'],
+            'tocTitleColor' => ['group' => 'colors', 'attribute' => 'title_color'],
+            'tocTitleBorderColor' => ['group' => 'colors', 'attribute' => 'title_border_color'],
+            'tocLinkColor' => ['group' => 'colors', 'attribute' => 'link_color'],
+            'tocLinkHoverColor' => ['group' => 'colors', 'attribute' => 'link_hover_color'],
+            'tocLinkHoverBackground' => ['group' => 'colors', 'attribute' => 'link_hover_background'],
+            'tocActiveBorderColor' => ['group' => 'colors', 'attribute' => 'active_border_color'],
+            'tocActiveBackgroundColor' => ['group' => 'colors', 'attribute' => 'active_background_color'],
+            'tocActiveTextColor' => ['group' => 'colors', 'attribute' => 'active_text_color'],
+            'tocScrollbarTrackColor' => ['group' => 'colors', 'attribute' => 'scrollbar_track_color'],
+            'tocScrollbarThumbColor' => ['group' => 'colors', 'attribute' => 'scrollbar_thumb_color'],
+
+            // Spacing
+            'tocContainerPadding' => ['group' => 'spacing', 'attribute' => 'container_padding'],
+            'tocMarginBottom' => ['group' => 'spacing', 'attribute' => 'margin_bottom'],
+            'tocTitlePaddingBottom' => ['group' => 'spacing', 'attribute' => 'title_padding_bottom'],
+            'tocTitleMarginBottom' => ['group' => 'spacing', 'attribute' => 'title_margin_bottom'],
+            'tocItemMarginBottom' => ['group' => 'spacing', 'attribute' => 'item_margin_bottom'],
+            'tocLinkPadding' => ['group' => 'spacing', 'attribute' => 'link_padding'],
+            'tocLevelThreePaddingLeft' => ['group' => 'spacing', 'attribute' => 'level_three_padding_left'],
+            'tocLevelFourPaddingLeft' => ['group' => 'spacing', 'attribute' => 'level_four_padding_left'],
+            'tocScrollbarWidth' => ['group' => 'spacing', 'attribute' => 'scrollbar_width'],
+
+            // Visual Effects
+            'tocBorderRadius' => ['group' => 'visual_effects', 'attribute' => 'border_radius'],
+            'tocBoxShadow' => ['group' => 'visual_effects', 'attribute' => 'box_shadow'],
+            'tocBorderWidth' => ['group' => 'visual_effects', 'attribute' => 'border_width'],
+            'tocLinkBorderRadius' => ['group' => 'visual_effects', 'attribute' => 'link_border_radius'],
+            'tocActiveBorderLeftWidth' => ['group' => 'visual_effects', 'attribute' => 'active_border_left_width'],
+            'tocTransitionDuration' => ['group' => 'visual_effects', 'attribute' => 'transition_duration'],
+            'tocScrollbarBorderRadius' => ['group' => 'visual_effects', 'attribute' => 'scrollbar_border_radius'],
+
+            // Behavior
+            'tocIsSticky' => ['group' => 'behavior', 'attribute' => 'is_sticky'],
+            'tocScrollOffset' => ['group' => 'behavior', 'attribute' => 'scroll_offset'],
+            'tocMaxHeight' => ['group' => 'behavior', 'attribute' => 'max_height'],
+        ];
+    }
+}