Use @gorhom/bottom-sheet for waypoint sheet

Replace custom View-based bottom sheet with @gorhom/bottom-sheet:
- Native gesture-driven drag, snap points, pan-down-to-close
- Proper safe area handling built in
- Wrap app with GestureHandlerRootView
- Add react-native-reanimated plugin to Expo config

Adds react-native-reanimated and react-native-gesture-handler as
native dependencies (requires new EAS build).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/mobile/app.config.ts

@@ -44,6 +44,7 @@ export default ({ config }: ConfigContext): ExpoConfig => ({
       project: "mobile",
     }],
     "expo-sqlite",
+    "react-native-reanimated",
   ],
   extra: {
     eas: {