test: setup coverage

Author: bitsnaps

package.json

@@ -12,7 +12,8 @@
     "start": "node bin/index.js",
     "test": "vitest run tests/*",
     "test:watch": "vitest --watch tests/*",
-    "version": "auto-changelog -p && git add CHANGELOG.md"
+    "version": "auto-changelog -p && git add CHANGELOG.md",
+    "coverage": "vitest run --coverage"
   },
   "engines": {
     "node": ">=18.0.0"
@@ -39,6 +40,7 @@
     "yargs-parser": "^21.1.1"
   },
   "devDependencies": {
+    "@vitest/coverage-v8": "2.1.8",
     "auto-changelog": "^2.5.0",
     "vitest": "^2.1.8"
   },