fix(deps): update nextra monorepo to v4

Author: renovate[bot]

docs/package.json

@@ -12,8 +12,8 @@
   "dependencies": {
     "@techstack/components": "1.3.364",
     "next": "15.2.1",
-    "nextra": "2.13.4",
-    "nextra-theme-docs": "2.13.4",
+    "nextra": "4.2.16",
+    "nextra-theme-docs": "4.2.16",
     "react": "18.3.1",
     "react-dom": "18.3.1"
   },