chore(deps): update dependency vitepress to v1.6.4

Author: renovate[bot]

package.json

@@ -158,7 +158,7 @@
     "tsx": "^4.11.2",
     "typescript": "^5.6.3",
     "typescript-eslint": "^8.4.0",
-    "vitepress": "1.6.3",
+    "vitepress": "1.6.4",
     "vitepress-plugin-llms": "^1.1.0",
     "vitest": "^2.1.5",
     "vue": "3.5.18",