fix(app): improve iOS PWA shell

packages/ui/src/assets/favicon/site.webmanifest

@@ -1,6 +1,9 @@
 {
   "name": "OpenCode",
   "short_name": "OpenCode",
+  "id": "/",
+  "start_url": "/",
+  "scope": "/",
   "icons": [
     {
       "src": "/web-app-manifest-192x192.png",
@@ -15,7 +18,7 @@
       "purpose": "maskable"
     }
   ],
-  "theme_color": "#ffffff",
-  "background_color": "#ffffff",
-  "display": "standalone"
+  "theme_color": "#080808",
+  "background_color": "#080808",
+  "display": "fullscreen"
 }

packages/ui/src/theme/context.tsx

@@ -152,10 +152,11 @@ function applyThemeCss(theme: DesktopTheme, themeId: string, mode: "light" | "da
   ensureThemeStyleElement().textContent = fullCss
   document.documentElement.dataset.theme = themeId
   document.documentElement.dataset.colorScheme = mode
+  document.documentElement.style.backgroundColor = isDark ? "#080808" : "#fafafa"
 
   // Update theme-color meta tag to match light/dark mode
   const meta = document.querySelector('meta[name="theme-color"]')
-  if (meta) meta.setAttribute("content", isDark ? "#131010" : "#F8F7F7")
+  if (meta) meta.setAttribute("content", isDark ? "#080808" : "#fafafa")
 }
 
 function cacheThemeVariants(theme: DesktopTheme, themeId: string) {