setup: initialize project with package.json, tsconfig, tsup, vitest, src skeleton, and test placeholders

vitest.config.ts

@@ -0,0 +1,19 @@
+import { defineConfig } from 'vitest/config';
+import path from 'node:path';
+
+export default defineConfig({
+  resolve: {
+    alias: {
+      '@': path.resolve(__dirname, 'src'),
+    },
+  },
+  test: {
+    globals: true,
+    include: ['test/**/*.test.ts'],
+    coverage: {
+      provider: 'v8',
+      include: ['src/**/*.ts'],
+      exclude: ['src/**/index.ts'],
+    },
+  },
+});