chore(deps): move the test runner to vitest 5

vitest and @vitest/coverage-v8 move from 4.1 to 5.0.3 together. Neither
config uses an option the major removed or changed: no projects, so the
new setupFiles concatenation does not apply; no browser mode; and the
integration config's forks pool, serial files and isolation keep their
meaning. Node 22.12 and Vite 6.4 are the new floors, and both are met.

package.json

@@ -122,7 +122,7 @@
     "@types/react-dom": "^19.3.0",
     "@types/web-push": "^3.6.4",
     "@vitejs/plugin-react": "^6.1.2",
-    "@vitest/coverage-v8": "^4.1.5",
+    "@vitest/coverage-v8": "^5.0.3",
     "ajv": "^8.20.0",
     "eslint": "^9",
     "eslint-config-next": "16.3.8",
@@ -137,6 +137,6 @@
     "testcontainers": "^12.2.0",
     "tw-animate-css": "^1.4.0",
     "typescript": "^6",
-    "vitest": "^4.1.11"
+    "vitest": "^5.0.3"
   }
 }