chore(deps): update react monorepo to v19

Author: renovate[bot]

package.json

@@ -48,8 +48,8 @@
     "@playwright/test": "1.54.2",
     "@replit/codemirror-lang-svelte": "6.0.0",
     "@types/node": "22.16.5",
-    "@types/react": "18.3.23",
-    "@types/react-dom": "18.3.7",
+    "@types/react": "19.1.9",
+    "@types/react-dom": "19.1.7",
     "@uiw/react-codemirror": "4.24.2",
     "@vitejs/plugin-react": "4.7.0",
     "astro": "5.12.8",
@@ -65,8 +65,8 @@
     "postcss-mixins": "12.1.2",
     "prettier": "3.6.2",
     "prettier-plugin-svelte": "3.4.0",
-    "react": "18.3.1",
-    "react-dom": "18.3.1",
+    "react": "19.1.1",
+    "react-dom": "19.1.1",
     "rehype-autolink-headings": "7.1.0",
     "rehype-slug": "6.0.0",
     "remark-toc": "9.0.0",