feat: add testing using vitest

vitest.config.ts

@@ -0,0 +1,12 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    globals: true,
+    environment: 'node',
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'json', 'html'],
+    },
+  },
+});