style: lighter inline code, black system bars for the installed app

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/index.html

@@ -4,7 +4,7 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
     <!-- Blue while loading (matches the splash screen); the app switches it to the theme background -->
-    <meta name="theme-color" content="#2563eb" />
+    <meta name="theme-color" content="#000000" />
     <meta name="mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-title" content="MindSift" />