Reapply "Add missing admin action files and navigation links"

This reverts commit 4d515bc400.

src/app/api/users/[username]/route.ts

@@ -10,10 +10,7 @@ import { prisma } from "@/lib/prisma";
 
 export const dynamic = "force-dynamic";
 
-export async function GET(
-  _req: Request,
-  { params }: { params: Promise<{ username: string }> },
-) {
+export async function GET(_req: Request, { params }: { params: Promise<{ username: string }> }) {
   const { username } = await params;
 
   try {