Add maskable icon with solid background for Windows taskbar

- Created icon-maskable.svg with full background (no transparency)
- Generated icon-512x512-maskable.png with 90% safe zone
- Updated manifest to use dedicated maskable icon
- Fixes white background issue on Windows taskbar/topbar

nuxt4/nuxt.config.ts

@@ -48,7 +48,7 @@ export default defineNuxtConfig({
           purpose: 'any'
         },
         {
-          src: '/icon-512x512.png',
+          src: '/icon-512x512-maskable.png',
           sizes: '512x512',
           type: 'image/png',
           purpose: 'maskable'

nuxt4/public/icon-maskable.svg

@@ -0,0 +1,35 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" fill="none">
+  <!-- Background gradient para maskable (fondo completo sin transparencia) -->
+  <defs>
+    <linearGradient id="grad1" x1="0%" y1="0%" x2="100%" y2="100%">
+      <stop offset="0%" style="stop-color:#00DC82;stop-opacity:1" />
+      <stop offset="100%" style="stop-color:#00A155;stop-opacity:1" />
+    </linearGradient>
+    <linearGradient id="grad2" x1="0%" y1="0%" x2="100%" y2="100%">
+      <stop offset="0%" style="stop-color:#4A90E2;stop-opacity:1" />
+      <stop offset="100%" style="stop-color:#2E5C8A;stop-opacity:1" />
+    </linearGradient>
+  </defs>
+
+  <!-- Fondo completo (sin transparencia para evitar el blanco en Windows) -->
+  <rect width="512" height="512" fill="url(#grad1)"/>
+
+  <!-- Contenido en el 80% central (safe zone para maskable icons) -->
+  <g transform="translate(256, 256) scale(0.9) translate(-256, -256)">
+    <!-- Shield shape (Authentik security) -->
+    <path d="M256 80 L380 140 L380 280 Q380 360 256 420 Q132 360 132 280 L132 140 Z"
+          fill="url(#grad2)" opacity="0.3"/>
+
+    <!-- Letter N (Nuxt) -->
+    <path d="M180 200 L180 340 L220 340 L220 260 L292 340 L332 340 L332 200 L292 200 L292 280 L220 200 Z"
+          fill="white" stroke="white" stroke-width="4"/>
+
+    <!-- Lock icon (Authentication) -->
+    <g transform="translate(340, 180)">
+      <rect x="-20" y="10" width="40" height="50" rx="5" fill="white" opacity="0.9"/>
+      <path d="M -15 10 L -15 -5 Q -15 -20 0 -20 Q 15 -20 15 -5 L 15 10"
+            stroke="white" stroke-width="6" fill="none" opacity="0.9"/>
+      <circle cx="0" cy="30" r="5" fill="#00DC82"/>
+    </g>
+  </g>
+</svg>