Reapply "Add missing admin action files and navigation links"

This reverts commit 4d515bc400.

src/app/api/online/count/route.ts

@@ -11,9 +11,7 @@ export const dynamic = "force-dynamic";
 
 export async function GET(_req: Request) {
   try {
-    const count = await cached("online_count", 10_000, () =>
-      prisma.user.count({ where: { online: "1" } }),
-    );
+    const count = await cached("online_count", 10_000, () => prisma.user.count({ where: { online: "1" } }));
     return apiJson({ count });
   } catch {
     return apiJson({ count: 0 });