refactor(web): reduz a complexidade do DownloadItem e adiciona testes com vitest

web/package.json

@@ -7,6 +7,8 @@
     "dev": "vite",
     "build": "tsc -b && vite build",
     "lint": "eslint .",
+    "test": "vitest run",
+    "typecheck": "tsc -b",
     "preview": "vite preview"
   },
   "dependencies": {
@@ -34,6 +36,7 @@
     "tailwindcss": "^4.1.18",
     "typescript": "~5.9.3",
     "typescript-eslint": "^8.46.4",
-    "vite": "^7.2.4"
+    "vite": "^7.2.4",
+    "vitest": "^5.0.3"
   }
 }