Preserve assistant message formatting on copy

packages/app/package.json

@@ -76,6 +76,7 @@
     "expo-updates": "~29.0.12",
     "fast-deep-equal": "^3.1.3",
     "lucide-react-native": "^0.546.0",
+    "markdown-it": "^10.0.0",
     "mnemonic-id": "^3.2.7",
     "qrcode": "^1.5.4",
     "react": "19.1.0",
@@ -103,6 +104,7 @@
   "devDependencies": {
     "@playwright/test": "^1.56.1",
     "@testing-library/react": "^16.3.2",
+    "@types/markdown-it": "^14.1.2",
     "@types/qrcode": "^1.5.6",
     "@types/react": "~19.2.0",
     "@types/ws": "^8.18.1",