Revert "Add missing admin action files and navigation links"

This reverts commit 41be6835bf.

src/app/admin/rooms/_lib/load-room.ts

@@ -1,15 +0,0 @@
-import { notFound } from 'next/navigation'
-import { prisma } from '@/lib/prisma'
-
-export async function loadRoom(id: string) {
-  const roomId = parseInt(id, 10)
-  if (Number.isNaN(roomId)) notFound()
-
-  const room = await prisma.room.findUnique({
-    where: { id: roomId },
-    include: { owner: { select: { id: true, username: true, look: true } } },
-  })
-
-  if (!room) notFound()
-  return room
-}