theme: rename theme_night class to theme_dark

Align the CSS class name with the public-facing terminology
introduced earlier in this branch (light / dark / auto). The
DARK_CLASS constant in lib/theme.ts and the inline pre-paint
script in index.html now use "dark"; scss/night.scss is renamed
to scss/dark.scss for symmetry.

No behavior change. The class is set only by lib/theme.ts and
the pre-paint script; nothing else consumed the old name.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: 2 people

index.html

@@ -30,17 +30,17 @@
     <link rel="mask-icon" href="./mask-icon.svg" color="#FFFFFF" />
     <meta name="theme-color" content="#ffffff" />
 
-    <!-- Keep storage key ("meshviewer.theme") and class name ("theme_night") in sync with lib/theme.ts -->
+    <!-- Keep storage key ("meshviewer.theme") and class name ("theme_dark") in sync with lib/theme.ts -->
     <script>
       try {
         var t = localStorage.getItem("meshviewer.theme");
         if (t === "dark" || (t !== "light" && matchMedia("(prefers-color-scheme: dark)").matches)) {
-          document.documentElement.classList.add("theme_night");
+          document.documentElement.classList.add("theme_dark");
         }
       } catch (e) {
         try {
           if (matchMedia("(prefers-color-scheme: dark)").matches) {
-            document.documentElement.classList.add("theme_night");
+            document.documentElement.classList.add("theme_dark");
           }
         } catch (_) {
           /* matchMedia unavailable; accept a light paint */

lib/theme.ts

@@ -2,7 +2,7 @@ type Theme = "light" | "dark" | "auto";
 
 // Keep STORAGE_KEY and DARK_CLASS in sync with the pre-paint inline script in index.html.
 const STORAGE_KEY = "meshviewer.theme";
-const DARK_CLASS = "theme_night";
+const DARK_CLASS = "theme_dark";
 const THEMES: Theme[] = ["light", "dark", "auto"];
 
 let inMemory: Theme = "auto";

scss/night.scss scss/dark.scssscss/night.scss renamed to scss/dark.scss

@@ -10,7 +10,7 @@ variables.$color-map-background: #0d151c;
 
 variables.$color-online: color.adjust(variables.$color-online, $lightness: 25%);
 
-.theme_night {
+.theme_dark {
   //@import 'modules/base';
   body,
   textarea,

scss/main.scss

@@ -27,4 +27,4 @@
 
 // Make adjustments in custom scss
 @use "custom/custom";
-@use "night";
+@use "dark";