fix(templates): simplify dark mode detection

Remove redundant prefers-color-scheme check after confirming dark mode via localStorage.

templates/base.html

@@ -4,7 +4,7 @@
 <head>
   <script>
     (function() {
-      if (localStorage.getItem('darkMode') === 'true' || (!localStorage.getItem('darkMode') && window.matchMedia('(prefers-color-scheme: dark)').matches)) {
+      if (localStorage.getItem('darkMode') === 'true') {
         document.documentElement.classList.add('dark');
       }
       if (localStorage.getItem('sidebarOpen') !== 'true') {