test(auth): add test-only auth instance with testUtils plugin and initial tests

package.json

@@ -11,7 +11,9 @@
     "db:migrate": "drizzle-kit migrate",
     "db:studio": "drizzle-kit studio",
     "db:push": "drizzle-kit push",
-    "db:seed": "bun run lib/db/seed.ts"
+    "db:seed": "bun run lib/db/seed.ts",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
     "@aws-sdk/client-s3": "^3.1036.0",
@@ -41,12 +43,14 @@
     "@types/pg": "^8.20.0",
     "@types/react": "^19",
     "@types/react-dom": "^19",
+    "@vitest/runner": "^4.1.5",
     "drizzle-kit": "^0.31.10",
     "eslint": "^9",
     "eslint-config-next": "16.2.4",
     "tailwindcss": "^4",
     "tsx": "^4.21.0",
-    "typescript": "^5"
+    "typescript": "^5",
+    "vitest": "^4.1.5"
   },
   "ignoreScripts": [
     "sharp",