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/CtaLetsTalk/Infrastructure/FieldMapping/CtaLetsTalkFieldMapper.php

@@ -0,0 +1,68 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Admin\CtaLetsTalk\Infrastructure\FieldMapping;
+
+use ROITheme\Admin\Shared\Domain\Contracts\FieldMapperInterface;
+
+/**
+ * Field Mapper para CTA Lets Talk
+ *
+ * RESPONSABILIDAD:
+ * - Mapear field IDs del formulario a atributos de BD
+ * - Solo conoce sus propios campos (modularidad)
+ */
+final class CtaLetsTalkFieldMapper implements FieldMapperInterface
+{
+    public function getComponentName(): string
+    {
+        return 'cta-lets-talk';
+    }
+
+    public function getFieldMapping(): array
+    {
+        return [
+            // Visibility
+            'ctaLetsTalkEnabled' => ['group' => 'visibility', 'attribute' => 'is_enabled'],
+            'ctaLetsTalkShowDesktop' => ['group' => 'visibility', 'attribute' => 'show_on_desktop'],
+            'ctaLetsTalkShowMobile' => ['group' => 'visibility', 'attribute' => 'show_on_mobile'],
+            'ctaLetsTalkShowOnPages' => ['group' => 'visibility', 'attribute' => 'show_on_pages'],
+
+            // Content
+            'ctaLetsTalkButtonText' => ['group' => 'content', 'attribute' => 'button_text'],
+            'ctaLetsTalkShowIcon' => ['group' => 'content', 'attribute' => 'show_icon'],
+            'ctaLetsTalkIconClass' => ['group' => 'content', 'attribute' => 'icon_class'],
+            'ctaLetsTalkModalTarget' => ['group' => 'content', 'attribute' => 'modal_target'],
+            'ctaLetsTalkAriaLabel' => ['group' => 'content', 'attribute' => 'aria_label'],
+
+            // Behavior
+            'ctaLetsTalkEnableModal' => ['group' => 'behavior', 'attribute' => 'enable_modal'],
+            'ctaLetsTalkCustomUrl' => ['group' => 'behavior', 'attribute' => 'custom_url'],
+            'ctaLetsTalkOpenNewTab' => ['group' => 'behavior', 'attribute' => 'open_in_new_tab'],
+
+            // Typography
+            'ctaLetsTalkFontSize' => ['group' => 'typography', 'attribute' => 'font_size'],
+            'ctaLetsTalkFontWeight' => ['group' => 'typography', 'attribute' => 'font_weight'],
+            'ctaLetsTalkTextTransform' => ['group' => 'typography', 'attribute' => 'text_transform'],
+
+            // Colors
+            'ctaLetsTalkBgColor' => ['group' => 'colors', 'attribute' => 'background_color'],
+            'ctaLetsTalkBgHoverColor' => ['group' => 'colors', 'attribute' => 'background_hover_color'],
+            'ctaLetsTalkTextColor' => ['group' => 'colors', 'attribute' => 'text_color'],
+            'ctaLetsTalkTextHoverColor' => ['group' => 'colors', 'attribute' => 'text_hover_color'],
+            'ctaLetsTalkBorderColor' => ['group' => 'colors', 'attribute' => 'border_color'],
+
+            // Spacing
+            'ctaLetsTalkPaddingTB' => ['group' => 'spacing', 'attribute' => 'padding_top_bottom'],
+            'ctaLetsTalkPaddingLR' => ['group' => 'spacing', 'attribute' => 'padding_left_right'],
+            'ctaLetsTalkMarginLeft' => ['group' => 'spacing', 'attribute' => 'margin_left'],
+            'ctaLetsTalkIconSpacing' => ['group' => 'spacing', 'attribute' => 'icon_spacing'],
+
+            // Visual Effects
+            'ctaLetsTalkBorderRadius' => ['group' => 'visual_effects', 'attribute' => 'border_radius'],
+            'ctaLetsTalkBorderWidth' => ['group' => 'visual_effects', 'attribute' => 'border_width'],
+            'ctaLetsTalkBoxShadow' => ['group' => 'visual_effects', 'attribute' => 'box_shadow'],
+            'ctaLetsTalkTransition' => ['group' => 'visual_effects', 'attribute' => 'transition_duration'],
+        ];
+    }
+}