Reapply "Add missing admin action files and navigation links"

This reverts commit 4d515bc400.

src/actions/admin-badges.ts

@@ -9,7 +9,9 @@ export async function giveBadge(formData: FormData): Promise<void> {
   await requireStaff();
 
   const userId = Number(formData.get("userId"));
-  const code = String(formData.get("code") ?? "").trim().slice(0, 32);
+  const code = String(formData.get("code") ?? "")
+    .trim()
+    .slice(0, 32);
   if (!(userId > 0) || code.length === 0) return;
 
   // Fire the emulator command so the badge appears live for online users.