Update react monorepo to v19

Author: renovate[bot]

package.json

@@ -23,8 +23,8 @@
     "ms": "^2.1.3",
     "next": "14.2.15",
     "openai": "^4.37.1",
-    "react": "^18",
-    "react-dom": "^18",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
     "react-markdown": "^9.0.1",
     "tailwind-merge": "^2.2.2",
     "tailwindcss-animate": "^1.0.7",