Add color scheme dark (#2835)

Author: benjaminleonard

index.html

@@ -2,7 +2,7 @@
   ~ This Source Code Form is subject to the terms of the Mozilla Public
   ~ License, v. 2.0. If a copy of the MPL was not distributed with this
   ~ file, you can obtain one at https://mozilla.org/MPL/2.0/.
-  ~  
+  ~
   ~ Copyright Oxide Computer Company
 -->
 
@@ -13,6 +13,7 @@
     <title>Oxide Console</title>
 
     <meta name="viewport" content="width=1050" />
+    <meta name="color-scheme" content="dark" />
 
     <link rel="icon" type="image/svg+xml" href="./app/assets/favicon.svg" />
     <link rel="icon" type="image/png" href="./app/assets/favicon.png" />