refactor(fonts): cambiar a system fonts - CERO flash

- Eliminar @font-face de Poppins (critical-bootstrap.css, css-global-fonts.css)
- Actualizar --bs-body-font-family a system font stack
- Desactivar font preload en CriticalCSSInjector.php
- Actualizar bootstrap-subset.min.css

System fonts garantizan carga instantánea sin parpadeo.

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

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

Assets/Css/critical-bootstrap.css

@@ -5,7 +5,7 @@
  * NO contiene CSS personalizado (ese va en critical-custom-temp.css - TIPO 3).
  *
  * Componentes Bootstrap incluidos:
- * - Fonts (@font-face Poppins)
+ * - System Fonts (CERO flash - sin @font-face externos)
  * - Variables CSS (:root)
  * - Resets (box-sizing, body)
  * - Container system
@@ -30,45 +30,29 @@
  */
 
 /* ==========================================================================
-   CRITICAL FONTS (Poppins - LCP optimization)
+   SYSTEM FONTS - CERO Flash (sin fuentes externas)
 
-   font-display: swap + preload = fuente carga rapido y siempre se muestra
-   size-adjust: 100.6% = fallback casi identico a Poppins (minimiza CLS)
+   Usa fuentes nativas del sistema operativo:
+   - macOS/iOS: -apple-system, BlinkMacSystemFont
+   - Windows: Segoe UI
+   - Android: Roboto
+   - Linux: Ubuntu/Cantarell
+   - Fallback: sans-serif
+
+   VENTAJAS:
+   - 0 KB descarga (fuentes ya instaladas)
+   - 0 flash/parpadeo (disponibles instantaneamente)
+   - Mejor rendimiento LCP/FCP
+   - Familiar para usuarios (fuentes nativas)
    ========================================================================== */
-@font-face {
-    font-family: 'Poppins Fallback';
-    src: local('Arial'), local('Helvetica Neue'), local('sans-serif');
-    size-adjust: 106%;
-    ascent-override: 105%;
-    descent-override: 35%;
-    line-gap-override: 10%;
-}
-@font-face {
-    font-family: 'Poppins';
-    src: url('/wp-content/themes/roi-theme/Assets/Fonts/poppins-v24-latin-regular.woff2') format('woff2');
-    font-weight: 400;
-    font-style: normal;
-    font-display: swap;
-}
-@font-face {
-    font-family: 'Poppins';
-    src: url('/wp-content/themes/roi-theme/Assets/Fonts/poppins-v24-latin-600.woff2') format('woff2');
-    font-weight: 600;
-    font-style: normal;
-    font-display: swap;
-}
-@font-face {
-    font-family: 'Poppins';
-    src: url('/wp-content/themes/roi-theme/Assets/Fonts/poppins-v24-latin-700.woff2') format('woff2');
-    font-weight: 700;
-    font-style: normal;
-    font-display: swap;
-}
 
 :root {
-    /* Fonts */
-    --font-primary: 'Poppins', 'Poppins Fallback', sans-serif;
-    --bs-body-font-family: 'Poppins', 'Poppins Fallback', sans-serif;
+    /* System Font Stack - CERO flash garantizado */
+    --font-system: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
+                   "Helvetica Neue", Arial, "Noto Sans", "Liberation Sans",
+                   sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
+    --font-primary: var(--font-system);
+    --bs-body-font-family: var(--font-system);
 
     /* Theme Colors (críticos para above-the-fold) */
     --color-navy-dark: #0E2337;