Add example Symfony Console application

nix/composer2nix/index.php

@@ -0,0 +1,20 @@
+<?php
+
+// https://symfony.com/doc/current/components/console/single_command_tool.html
+
+require __DIR__.'/vendor/autoload.php';
+
+use Symfony\Component\Console\Attribute\Argument;
+use Symfony\Component\Console\Attribute\Option;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\SingleCommandApplication;
+
+(new SingleCommandApplication())
+    ->setName('My Super Command') // Optional
+    ->setVersion('1.0.0') // Optional
+    ->setCode(function (OutputInterface $output, #[Argument] string $foo = 'The directory', #[Option] string $bar = ''): int {
+        // output arguments and options
+
+        return 0;
+    })
+    ->run();