feat(critical-css): implementar TIPO 4 y TIPO 5 - CSS Below-the-fold y Lazy Loading

## TIPO 4: CSS Below-the-fold (Critical Variables + Responsive)
- Inyecta variables CSS críticas inline en wp_head P:-1
- Inyecta media queries críticas inline en wp_head P:2 (corregido de P:1)
- Auto-regeneración cuando archivos fuente cambian (filemtime check)
- Cache en Assets/CriticalCSS/ para evitar lecturas repetidas
- Comando WP-CLI: wp roi-theme generate-critical-css

Archivos TIPO 4:
- Public/CriticalCSS/Domain/Contracts/ - Interfaces (DIP)
- Public/CriticalCSS/Application/UseCases/GetCriticalCSSUseCase.php
- Public/CriticalCSS/Infrastructure/Cache/CriticalCSSFileCache.php
- Public/CriticalCSS/Infrastructure/Services/CriticalCSSExtractor.php
- Public/CriticalCSS/Infrastructure/Services/CriticalCSSInjector.php
- bin/generate-critical-css.php

## TIPO 5: CSS No Crítico (Lazy Loading)
- Animaciones CSS: carga 2s después de page load via requestIdleCallback
- Print CSS: carga solo al imprimir via beforeprint event
- Fallback <noscript> para usuarios sin JavaScript
- Safari fallback: setTimeout cuando requestIdleCallback no disponible

Archivos TIPO 5:
- Assets/Js/lazy-css-loader.js
- Public/LazyCSSLoader/Infrastructure/Contracts/LazyCSSRegistrarInterface.php
- Public/LazyCSSLoader/Infrastructure/Services/LazyCSSRegistrar.php

## Fix: Colisión de prioridades wp_head
Antes: TIPO 1 (P:1), TIPO 4 responsive (P:1), TIPO 3 (P:2) - CONFLICTO
Después: TIPO 1 (P:1), TIPO 4 responsive (P:2), TIPO 3 (P:3) - OK

Nuevo orden de prioridades:
P:-1 roi-critical-variables (TIPO 4)
P:0  roi-critical-bootstrap (TIPO 2)
P:1  roi-critical-css (TIPO 1)
P:2  roi-critical-responsive (TIPO 4)
P:3  roi-custom-critical-css (TIPO 3)
P:5  roi-theme-layout-css (ThemeSettings)

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

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

Assets/CriticalCSS/responsive.critical.css

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+@media (max-width:575.98px){:root{--bs-gutter-x:1rem}body{font-size:14px}h1{font-size:24px}h2{font-size:20px}h3{font-size:18px}.container-fluid{padding:0 10px}.navbar{padding:0.5rem 0}.navbar-brand{font-size:18px}main{padding:0.5rem}.sidebar{margin-top:2rem}table{font-size:12px;margin-bottom:1rem;overflow-x:auto}.table-responsive{margin-bottom:1rem}.btn{padding:0.375rem 0.75rem;font-size:14px}.btn-lg{padding:0.5rem 1rem;font-size:16px}.card{margin-bottom:1rem}.form-group{margin-bottom:1rem}.form-control{padding:0.375rem 0.75rem;font-size:16px}.modal-dialog{margin:0.5rem}.modal-content{border-radius:4px}img{max-width:100%;height:auto}ul,ol{padding-left:1.5rem}.mt-1,.my-1{margin-top:0.25rem !important}.mb-1,.my-1{margin-bottom:0.25rem !important}.p-1{padding:0.25rem !important}}@media (min-width:576px){body{font-size:14px}h1{font-size:28px}h2{font-size:22px}h3{font-size:18px}}@media (min-width:768px){body{font-size:15px}h1{font-size:32px}h2{font-size:26px}h3{font-size:20px}.row-md-2{display:grid;grid-template-columns:1fr 1fr;gap:1.5rem}.navbar{padding:1rem 0}.main-content{display:grid;grid-template-columns:1fr 300px;gap:2rem}.main-content.no-sidebar{grid-template-columns:1fr}}@media (min-width:992px){body{font-size:16px}h1{font-size:36px}h2{font-size:28px}h3{font-size:22px}.row-lg-3{display:grid;grid-template-columns:repeat(3,1fr);gap:2rem}.main-content{display:grid;grid-template-columns:1fr 300px;gap:2rem}.main-content.with-left-sidebar{grid-template-columns:250px 1fr 300px}.content-wrapper{max-width:1200px;margin:0 auto}}