feat(api): implement recaptcha v3 anti-spam protection

- Add RecaptchaValidatorInterface and RecaptchaResult entity in Domain
- Create RecaptchaValidationService in Application layer
- Implement GoogleRecaptchaValidator for API integration
- Add recaptcha-settings schema and admin FormBuilder
- Integrate reCAPTCHA validation in NewsletterAjaxHandler
- Integrate reCAPTCHA validation in ContactFormAjaxHandler
- Update FooterRenderer and ContactFormRenderer with reCAPTCHA scripts
- Configure DIContainer with RecaptchaValidationService injection

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

Admin/Infrastructure/Ui/AdminDashboardRenderer.php

@@ -128,6 +128,11 @@ final class AdminDashboardRenderer implements DashboardRendererInterface
                 'label' => 'AdSense',
                 'icon' => 'bi-megaphone',
             ],
+            'recaptcha-settings' => [
+                'id' => 'recaptcha-settings',
+                'label' => 'reCAPTCHA',
+                'icon' => 'bi-shield-check',
+            ],
             'custom-css-manager' => [
                 'id' => 'custom-css-manager',
                 'label' => 'CSS Personalizado',