fix: pin react-dom to 19.1.0 to prevent npm resolving 19.2.5

expo-router@6.0.23 declares react-dom as peerOptional; without an explicit
pin npm resolves react-dom@19.2.5 (latest) which conflicts with react@19.1.0.
The SDK 54 template pins both to 19.1.0 — mirroring that here.

mobile/package.json

@@ -23,6 +23,7 @@
     "expo-splash-screen": "~31.0.13",
     "expo-status-bar": "~3.0.9",
     "react": "19.1.0",
+    "react-dom": "19.1.0",
     "react-native": "0.81.5",
     "react-native-safe-area-context": "~5.6.0",
     "react-native-screens": "~4.16.0",