feat(create): reject non-empty target directories

Made-with: Cursor

packages/create/src/paths.ts

@@ -0,0 +1,17 @@
+import fs from "node:fs";
+import path from "node:path";
+import { CliError } from "./errors.js";
+
+export function resolveTargetRoot(cwd: string, dir: string): string {
+  const abs = path.resolve(cwd, dir);
+  if (fs.existsSync(abs)) {
+    const entries = fs.readdirSync(abs);
+    if (entries.length > 0) {
+      throw new CliError(
+        `Target directory is not empty: ${abs}`,
+        "INVALID_INPUT"
+      );
+    }
+  }
+  return abs;
+}