Add folder game, file browser UI, and automated tests.

Introduces a localStorage-backed messy-desktop challenge with sub-steps,
drag-and-drop and Places/Back navigation, IBM Plex Mono, and a /api/health
endpoint. Adds Vitest coverage for the API and level logic plus Playwright
smoke tests.

Made-with: Cursor

vitest.config.ts

@@ -0,0 +1,22 @@
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { defineConfig } from "vitest/config";
+
+const root = path.dirname(fileURLToPath(import.meta.url));
+
+export default defineConfig({
+  resolve: {
+    alias: {
+      "~": path.join(root, "src"),
+    },
+  },
+  test: {
+    environment: "node",
+    include: ["tests/**/*.test.ts"],
+    exclude: ["e2e/**", "node_modules/**"],
+    env: {
+      NODE_ENV: "test",
+      SKIP_ENV_VALIDATION: "1",
+    },
+  },
+});