Fix flash of wrong theme on initial UI load (#485)

Co-authored-by: Tonya <tonya@tokia.dev>

frontend/nuxt.config.ts

@@ -20,6 +20,12 @@ export default defineNuxtConfig({
     },
   },
 
+  app: {
+    head: {
+      script: [{ src: "/set-theme.js" }],
+    },
+  },
+
   css: ["@/assets/css/main.css"],
 
   pwa: {

frontend/public/set-theme.js

@@ -0,0 +1,9 @@
+try {
+  console.log('Setting theme');
+  const theme = JSON.parse(
+    localStorage.getItem('homebox/preferences/location')
+  ).theme;
+  if (theme) document.documentElement.setAttribute('data-theme', theme);
+} catch (e) {
+  console.error('Failed to set theme', e);
+}