chore(sandbox): sandbox cleanup (#797)

Co-authored-by: Christian Pillsbury <cpillsbury@mux.com>

packages/sandbox/scripts/setup.ts

@@ -0,0 +1,27 @@
+import { copyFileSync, existsSync, mkdirSync, readdirSync, statSync } from 'node:fs';
+import { resolve } from 'node:path';
+
+const root = resolve(import.meta.dirname, '..');
+const templatesDir = resolve(root, 'templates');
+const srcDir = resolve(root, 'src');
+
+/** Recursively copy template files into `src/`, preserving relative paths. */
+function mirror(dir: string) {
+  for (const entry of readdirSync(dir)) {
+    const templatePath = resolve(dir, entry);
+    const targetPath = resolve(srcDir, templatePath.slice(templatesDir.length + 1));
+
+    if (statSync(templatePath).isDirectory()) {
+      mkdirSync(targetPath, { recursive: true });
+      mirror(templatePath);
+      continue;
+    }
+
+    if (!existsSync(targetPath)) {
+      copyFileSync(templatePath, targetPath);
+      console.log(`Created ${targetPath.slice(root.length + 1)}`);
+    }
+  }
+}
+
+mirror(templatesDir);