fix(rail-ads): Position rails fixed at viewport edges

- Changed Rail Ads positioning from container-width-based formula to fixed 15px from viewport edges
- Rails no longer move inward when container width is reduced
- Fixes overlap issue when layout width setting changes

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

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

Public/AdsensePlacement/Infrastructure/Ui/AdsensePlacementRenderer.php

@@ -322,16 +322,15 @@ final class AdsensePlacementRenderer
             'transition' => 'top 0.2s ease-out',
         ]);
 
-        // Posicion rail izquierdo - usar max() para evitar valores negativos
-        // Usa CSS variable --roi-container-width-numeric de ThemeSettings (fallback 1320px)
-        // Formula: max(10px, calc((100vw - containerWidth) / 2 - (width + 20)px))
+        // Posicion rail izquierdo - FIJO en el borde del viewport
+        // Los Rails NO dependen del container width, siempre estan a 15px del borde
         $cssRules[] = $this->cssGenerator->generate('.roi-rail-ad-left', [
-            'left' => 'max(10px, calc((100vw - var(--roi-container-width-numeric, 1320px)) / 2 - ' . ($width + 20) . 'px))',
+            'left' => '15px',
         ]);
 
-        // Posicion rail derecho - usar max() para consistencia
+        // Posicion rail derecho - FIJO en el borde del viewport
         $cssRules[] = $this->cssGenerator->generate('.roi-rail-ad-right', [
-            'right' => 'max(10px, calc((100vw - var(--roi-container-width-numeric, 1320px)) / 2 - ' . ($width + 20) . 'px))',
+            'right' => '15px',
         ]);
 
         // Media query para ocultar en pantallas < 1600px