Reapply "Add missing admin action files and navigation links"

This reverts commit 4d515bc400.

src/components/theme-switcher.tsx

@@ -9,8 +9,8 @@ import { useState } from "react";
  * theme before paint to avoid a flash — this component only reflects/toggles it.
  */
 export function ThemeSwitcher() {
-  const [dark, setDark] = useState(() =>
-    typeof window !== "undefined" && document.documentElement.classList.contains("dark"),
+  const [dark, setDark] = useState(
+    () => typeof window !== "undefined" && document.documentElement.classList.contains("dark"),
   );
 
   function toggle() {