feat(docs): enhance documentation and UI consistency

- Updated the index.html to dynamically set the theme color based on user selection, improving user experience during theme switching.
- Modified proxy.ts to include 'icon.png' in the matcher for better asset handling.
- Added a new icon.png file for enhanced branding.
- Improved metadata in layout.tsx and page.tsx files for better clarity and consistency in documentation.
- Updated various documentation files to reflect the new branding of 'Cursor Byok' and ensure consistent terminology throughout.
- Removed outdated blog entries and added new content to better align with the current product direction.

apps/desktop/demo/index.html

@@ -3,7 +3,6 @@
   <head>
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
-    <meta name="theme-color" content="#141414" />
     <style>
       html,
       body,
@@ -11,9 +10,20 @@
         width: 100%;
         height: 100%;
         margin: 0;
-        background: #141414;
+        background: var(--boot-bg, #141414);
       }
     </style>
+    <script>
+      // 在应用样式加载前按主题参数铺底色，避免切换 poster 时闪出错误颜色
+      (function () {
+        var light = new URLSearchParams(location.search).get("theme") === "default-light";
+        document.documentElement.style.setProperty("--boot-bg", light ? "#f5f5f5" : "#141414");
+        var meta = document.createElement("meta");
+        meta.name = "theme-color";
+        meta.content = light ? "#f5f5f5" : "#141414";
+        document.head.appendChild(meta);
+      })();
+    </script>
     <title>Cursor BYOK 产品演示</title>
   </head>
   <body>