feat: add app serve

src/program.ts

@@ -0,0 +1,13 @@
+import { program, Command } from 'commander';
+import fs from 'fs';
+
+// 将多个子命令加入主程序中
+program.name('app').description('A CLI tool with envison').version('0.0.3');
+
+const ls = new Command('ls').description('List files in the current directory').action(() => {
+  console.log('List files');
+  console.log(fs.readdirSync(process.cwd()));
+});
+program.addCommand(ls);
+
+export { program, Command };