Add Dockerfile for application setup, update next.config.ts for standalone output, enhance documentation for FFMPEG_PATH, and implement ffmpeg location flag in download functionality

next.config.ts

@@ -1,7 +1,7 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
-  /* config options here */
+  output: "standalone",
 };
 
 export default nextConfig;