feat(cli): add help subcommand to show usage information

index.ts

@@ -535,6 +535,11 @@ async function main() {
     return;
   }
 
+  if (subcommand === "help") {
+    showHelp();
+    return;
+  }
+
   if (subcommand === "commit") {
     const autoMode = args.includes("--auto") || args.includes("-a");
     const dryRun = args.includes("--dry-run") || args.includes("-d");