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/SocialShare/Infrastructure/FieldMapping/SocialShareFieldMapper.php

@@ -0,0 +1,81 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Admin\SocialShare\Infrastructure\FieldMapping;
+
+use ROITheme\Admin\Shared\Domain\Contracts\FieldMapperInterface;
+
+/**
+ * Field Mapper para Social Share
+ *
+ * RESPONSABILIDAD:
+ * - Mapear field IDs del formulario a atributos de BD
+ * - Solo conoce sus propios campos (modularidad)
+ */
+final class SocialShareFieldMapper implements FieldMapperInterface
+{
+    public function getComponentName(): string
+    {
+        return 'social-share';
+    }
+
+    public function getFieldMapping(): array
+    {
+        return [
+            // Visibility
+            'socialShareEnabled' => ['group' => 'visibility', 'attribute' => 'is_enabled'],
+            'socialShareShowOnDesktop' => ['group' => 'visibility', 'attribute' => 'show_on_desktop'],
+            'socialShareShowOnMobile' => ['group' => 'visibility', 'attribute' => 'show_on_mobile'],
+            'socialShareShowOnPages' => ['group' => 'visibility', 'attribute' => 'show_on_pages'],
+
+            // Content
+            'socialShareShowLabel' => ['group' => 'content', 'attribute' => 'show_label'],
+            'socialShareLabelText' => ['group' => 'content', 'attribute' => 'label_text'],
+
+            // Networks
+            'socialShareFacebook' => ['group' => 'networks', 'attribute' => 'show_facebook'],
+            'socialShareFacebookUrl' => ['group' => 'networks', 'attribute' => 'facebook_url'],
+            'socialShareInstagram' => ['group' => 'networks', 'attribute' => 'show_instagram'],
+            'socialShareInstagramUrl' => ['group' => 'networks', 'attribute' => 'instagram_url'],
+            'socialShareLinkedin' => ['group' => 'networks', 'attribute' => 'show_linkedin'],
+            'socialShareLinkedinUrl' => ['group' => 'networks', 'attribute' => 'linkedin_url'],
+            'socialShareWhatsapp' => ['group' => 'networks', 'attribute' => 'show_whatsapp'],
+            'socialShareWhatsappNumber' => ['group' => 'networks', 'attribute' => 'whatsapp_number'],
+            'socialShareTwitter' => ['group' => 'networks', 'attribute' => 'show_twitter'],
+            'socialShareTwitterUrl' => ['group' => 'networks', 'attribute' => 'twitter_url'],
+            'socialShareEmail' => ['group' => 'networks', 'attribute' => 'show_email'],
+            'socialShareEmailAddress' => ['group' => 'networks', 'attribute' => 'email_address'],
+
+            // Colors
+            'socialShareLabelColor' => ['group' => 'colors', 'attribute' => 'label_color'],
+            'socialShareBorderTopColor' => ['group' => 'colors', 'attribute' => 'border_top_color'],
+            'socialShareButtonBg' => ['group' => 'colors', 'attribute' => 'button_background'],
+            'socialShareFacebookColor' => ['group' => 'colors', 'attribute' => 'facebook_color'],
+            'socialShareInstagramColor' => ['group' => 'colors', 'attribute' => 'instagram_color'],
+            'socialShareLinkedinColor' => ['group' => 'colors', 'attribute' => 'linkedin_color'],
+            'socialShareWhatsappColor' => ['group' => 'colors', 'attribute' => 'whatsapp_color'],
+            'socialShareTwitterColor' => ['group' => 'colors', 'attribute' => 'twitter_color'],
+            'socialShareEmailColor' => ['group' => 'colors', 'attribute' => 'email_color'],
+
+            // Typography
+            'socialShareLabelFontSize' => ['group' => 'typography', 'attribute' => 'label_font_size'],
+            'socialShareIconFontSize' => ['group' => 'typography', 'attribute' => 'icon_font_size'],
+
+            // Spacing
+            'socialShareMarginTop' => ['group' => 'spacing', 'attribute' => 'container_margin_top'],
+            'socialShareMarginBottom' => ['group' => 'spacing', 'attribute' => 'container_margin_bottom'],
+            'socialSharePaddingTop' => ['group' => 'spacing', 'attribute' => 'container_padding_top'],
+            'socialSharePaddingBottom' => ['group' => 'spacing', 'attribute' => 'container_padding_bottom'],
+            'socialShareLabelMarginBottom' => ['group' => 'spacing', 'attribute' => 'label_margin_bottom'],
+            'socialShareButtonsGap' => ['group' => 'spacing', 'attribute' => 'buttons_gap'],
+            'socialShareButtonPadding' => ['group' => 'spacing', 'attribute' => 'button_padding'],
+
+            // Visual Effects
+            'socialShareBorderTopWidth' => ['group' => 'visual_effects', 'attribute' => 'border_top_width'],
+            'socialShareButtonBorderWidth' => ['group' => 'visual_effects', 'attribute' => 'button_border_width'],
+            'socialShareButtonBorderRadius' => ['group' => 'visual_effects', 'attribute' => 'button_border_radius'],
+            'socialShareTransitionDuration' => ['group' => 'visual_effects', 'attribute' => 'transition_duration'],
+            'socialShareHoverBoxShadow' => ['group' => 'visual_effects', 'attribute' => 'hover_box_shadow'],
+        ];
+    }
+}