Merge feature/responsive-layout-refactor into modular for desktop layouts.

Co-authored-by: Cursor <cursoragent@cursor.com>

index.html

@@ -10,6 +10,39 @@
         <meta name="theme-color" content="#ffffff">
         <meta name="enamad" content="44889195">
         <title></title>
+    <script>
+      (function () {
+        if (window.matchMedia('(min-width: 768px)').matches) {
+          document.documentElement.classList.add('app-layout--desktop')
+        }
+      })()
+    </script>
+    <style>
+      /* Critical: full-viewport splash before Vue/CSS hydrate */
+      html, body, #app {
+        margin: 0;
+        padding: 0;
+        min-height: 100vh;
+      }
+      @media (min-width: 768px) {
+        html, body, #app {
+          width: 100%;
+          max-width: none;
+        }
+        body {
+          display: block !important;
+        }
+      }
+      .app-splash-screen {
+        position: fixed;
+        inset: 0;
+        width: 100vw;
+        min-height: 100vh;
+        left: 0 !important;
+        right: 0 !important;
+        z-index: 2147483646;
+      }
+    </style>
 
     </head>
 <body>