🧪 Added Vitest configuration with coverage

vitest.config.ts

@@ -0,0 +1,10 @@
+import { defineConfig } from 'vitest/config';
+export default defineConfig({
+  test: {
+    coverage: {
+      reporter: ['text', 'html', 'lcov'],
+      include: ['src/**/*.ts'],
+      exclude: ['src/**/*.test.ts', 'test/**'],
+    },
+  },
+});