refactor(admin) : remove auto detect followers and use validPlatforms instead

app/admin/backend/page.tsx

@@ -1,17 +1,9 @@
 import { AdminShellServer } from "@/components/admin-shell-server";
-import { readdirSync } from "fs";
-import { join } from "path";
 import { BackendClient } from "./client";
-
 export const dynamic = "force-dynamic";
+const platforms = ["youtube", "roblox", "discord", "tiktok"];
 
 export default async function BackendPage() {
-  // Auto-discover platform files from lib/followers/
-  const dir = join(process.cwd(), "lib", "followers");
-  const platforms = readdirSync(dir)
-    .filter((f) => f.endsWith(".ts") && f !== "index.ts")
-    .map((f) => f.replace(".ts", ""));
-
   // Read current cached counts from Redis
   let counts: Record<string, number | null> = {};
   try {